Blood pressure measuring apparatus

ABSTRACT

An apparatus for measuring a blood pressure of a living subject, including a blood pressure measuring device which measures a blood pressure value of the subject, a first memory which stores a plurality of blood pressure values measured by the blood pressure measuring device, in an order of measurement of the blood pressure values, a pulse wave detecting device which detects a pulse wave produced from an arterial vessel of the subject in synchronism with heartbeat of the subject while each of the blood pressure values is measured by the blood pressure measuring device, a second memory which stores a waveform of the pulse wave detected by the pulse wave detecting device, in the order, the second memory storing the respective waveforms of the pulse waves each of which is detected by the pulse wave detecting device while a corresponding one of the blood pressure values is measured by the blood pressure measuring device, and an output device which outputs the blood pressure values stored in the first memory, in the order, and a plurality of curves respectively representing the waveforms stored in the second memory, in the order, in a side-by-side relation with each other.

This is a Division of application Ser. No. 08/799,831, filed Feb. 13,1997, which is a divisional application of U.S. application Ser. No.08/391,701, filed Feb. 21, 1995, which is now U.S. Pat. No. 5,649,536.The entire disclosure of the prior application is hereby incorporated byreference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the improvements of a blood pressuremeasuring apparatus which measures a blood pressure value of a livingsubject such as a patient.

2. Related Art Statement

There is known an automatic blood pressure (BP) measuring apparatuswhich carries out BP measurements on a patient, accumulatively stores ameasured BP value or values obtained in each BP measurement, andprovides a graphic representation of the stored BP values arranged inthe order of measurement. An example of the BP measuring apparatus isdisclosed in Non-Examined Japanese Patent Application laid open underPublication No. 5(1993)-137698. The BP apparatus enables the patient toeasily recognize the time change of the measured BP values and correctlyjudge whether he or she is in a healthy condition. When the patientfeels tight in the chest, such a light attack may, however, betransient, so that the patient may fail to recognize that he or shepossibly has a serious heart disease. Even if the patient may reach therecognition and consult a doctor, then the patient may no longer haveany subjective symptom and may appear to the doctor to have no medicalproblem. In this case, the doctor may make a diagnosis based oninsufficient examination data, e.g., BP values only. If the prior BPapparatus is used to obtain the BP values of the patient, however, theBP apparatus provides only the measured BP values of the patient, oronly the time change of the measured BP values. With those data, thepatient may suspect that he or she may have hypertension, but thepatient cannot make a self-diagnosis, or the doctor cannot make amedical diagnosis, that he or she may have a heart disease. If thepatient continues his or her life without receiving any medicaltreatments, he or she might be brought into a serious condition.

There is also known an automatic BP measuring apparatus which has a BPmeasuring device for automatically measuring a BP value or values of aliving body, and a BP-value storing device for accumulatively storingthe BP values measured by the BP measuring device from the living body.The BP measuring apparatus outputs the BP values accumulatively storedin the BP-value storing device, each time a new BP value or values ofthe subject is/are measured by the BP measuring device. Thus, the livingbody can easily recognize the time change of his or her BP values andeffectively utilize the BP values for his or her health control.However, in the case where the BP values output from the BP apparatus donot fall within a normal BP range and care should be taken of the livingbody, just the marshalling of figures would give only a weak visualimpression to the living body. Even if the living body may recognize hisor her blood pressure abnormality, he or she is likely to forget it.While it is possible to output a pictorial image together with the BPvalues to give a stronger visual impression to the living body, it needsmuch time and effort to prepare the pictorial image or images. Moreover,in the case where a doctor gives a blood pressure-treating medicine to apatient after having made a diagnosis based on measured BP values, itmay be somewhat cumbersome for the doctor to explain the directions foruse of the medicine, the objects of administration of the same, andother necessary items.

Next, there is known an arm belt which is, either manually or using awinding device, wound around an upper arm of a living body or subjectand which has an inflatable bag to which a pressurized air is suppliedto press the arteries of the arm and measure a BP value or values of thesubject. The supplying of the air to the bag is effected after the beltis wound around subject's arm, and the measurement of BP values iscarried out while the air pressure of the bag is changed. It ispreferred that the belt be wound around the arm such that three fingerscan be inserted between the skin of the arm and the inside surface ofthe belt. However, since the upper arm of the subject around which thearm belt is wound is easily deformable, a certain level of skill isneeded for winding the belt wound the arm with a preferable pressingforce and measuring a BP value or values of the subject with accuracy.Hence, there has been used a winding device which automatically winds anarm belt around an upper arm of a living subject. The automatic windingdevice has a cylindrical arm receiver in which the belt taking acylindrical shape is provided, and has a drive device such as a motorfor tightening the belt. After the subject inserts his or her arm intothe belt inside the receiver through one end of the receiver, the drivedevice is operated to tighten the belt and thereby reduce the insidediameter of the cylindrical belt. Thus, the arm belt is automaticallywound around the subject's upper arm. When a BP measurement is carriedout using the automatic winding device, it is required that the arteriesof the upper arm of the subject be uniformly pressed by the arm belt. Tothis end, generally, an elbow rest is provided outside the other end ofthe arm receiver, and the subject inserts his or her arm such that theelbow of the arm rests on the rest. The diameter of the belt is reducedwhen the subject is taking such a posture that the upper arm is not incontact with the inner wall of the above-mentioned one end of thereceiver. That is, it is preferred that the longitudinal axis line ofthe upper arm of the subject be kept substantially parallel to thecentral axis line of the cylindrical arm receiver. However, ordering thesubject to change his or her natural posture to the above-mentionedposture may result in forcing the subject to take an unnatural posture,depending upon the conformation of his or her body. This problem isexaggerated in particular for patients or aged persons who are not sofree to change their postures. In the latter cases, the accuracy of BPmeasurements may be lowered.

There is known a BP monitor apparatus which monitors the blood pressureof a living subject. The BP monitor apparatus includes an automatic BPmeasuring device including an inflatable cuff adapted to be wound arounda body portion of the subject. The automatic BP measuring device isiteratively started to measure a BP value or values of the subject.Thus, the BP monitor apparatus carries out BP measurements periodically,i.e., at a prescribed measurement period. However, if the measurementperiod is prescribed at so short a period to improve the reliability ofthe BP monitoring, the frequency of pressing of the subject's bodyportion with the cuff is increased so that the subject feels a heavyburden. In this situation, there has been proposed a BP monitorapparatus which increases the pressure of an inflatable cuff woundaround a body portion of a living subject, up to a prescribed targetpressure value, detects a pulse wave as a pressure oscillation producedin the cuff, and continuously estimates a BP value or values based on amagnitude or magnitudes of each of successive heartbeat-synchronouspulses of the pulse wave. Examples of this BP monitor apparatus aredisclosed in Non-Examined Japanese Patent Applications No.61(1986)-103432 and No. 60(1985)-241422. In the latter case, however, ifthe target pressure is prescribed at as low as possible a value toreduce the burden to the subject, it might be difficult to detect thechange of respective amplitudes of successive pulses of the pulse wavecorresponding to the change of BP values of the subject. That is, thereliability of the BP monitoring is lowered. The pulse amplitudesdetected from the cuff set on people having normal blood pressure changewith the cuff pressure so as to have an envelope indicated at solid linein FIG. 29, whereas the pulse amplitudes obtained from people having lowblood pressure change with the cuff pressure so as to have an envelopeindicated at broken line. Since the amount of change of the pulseamplitudes with respect to the amount of change of the BP values of asubject is more or less small where the pulse amplitudes are obtained ata relatively low cuff pressure such as a value, P_(K), shown in FIG. 29,the reliability of the BP monitoring at the low cuff pressure P_(K) isinsufficiently low.

Furthermore, there is known an automatic BP measuring apparatus whichquickly increases the pressure of an inflatable cuff wound around a bodyportion of a living subject, up to a target pressure value at which theinflated cuff stops the blood flow through the arteries of the bodyportion, subsequently slowly decreases the cuff pressure at a rate of 2to 3 mmHg/sec, and measures a BP value or values of the subject duringthe slow decreasing of the cuff pressure. There are known two BPmeasuring techniques, i.e., oscillometric method and Korotkoff-soundmethod. In the oscillometric method, the pressure oscillation producedin the cuff during the slow decreasing of the cuff pressure is detectedas a pulse wave, and the systolic and diastolic BP values of the subjectare determined based on the change of respective amplitudes ofsuccessive heartbeat-synchronous pulses of the pulse wave. In theKorotkoff-sound method, the Korotkoff sounds, i.e., blood-flow soundsproduced from the arteries of the body portion during the slowdecreasing of the cuff pressure are detected using a microphone, and thesystolic and diastolic BP values of the subject are determined based onthe two cuff-pressure values at which the first and last Korotkoffsounds are detected, respectively. In these BP measuring methods, theaccuracy of measurement of BP values depends on the amount of change ofthe cuff pressure corresponding to the interval of occurrence of thesuccessive pulses of the pulse wave or the successive Korotkoff sounds.Therefore, for measuring the BP value or values of the subject withaccuracy, the automatic BP measuring apparatus carries out the BPmeasurement while the cuff pressure is slowly decreased. However, sincein the prior BP measuring apparatus the cuff pressure is slowlydecreased in carrying out the BP measurement, it takes about twentyseconds to obtain the measured BP value or values of the subject. Beforethis slow cuff-pressure decreasing, no BP value is available to amedical worker such as a doctor. In the case where a doctor should makea quick decision on an emergency patient, or in the case where a targetvalue higher by a prescribed value than the systolic BP value of asubject should be determined while the cuff pressure is quicklyincreased, so that the cuff pressure is stopped at the thus determinedtarget value, it is required that a BP value of the subject be known,even though it is rough, before a BP measurement is carried out duringthe slow decreasing of the cuff pressure.

Moreover, there is known the oscillometric BP measuring method in whichheartbeat-synchronous signal waves generated from arteries of a livingsubject are collected while the pressure of an inflatable cuff appliedto the arteries is changed, the respective amplitudes of the signalwaves are determined to provide a series of wave amplitudes arranged inthe order of generation of the signal waves, and a BP value of thesubject is determined based on a change of the series of wave amplitudesaccording to a prescribed software algorithm. An example of the BPmeasuring method is disclosed in Examined Japanese Patent Applicationlaid open for opposition under Publication No. 2(1990)-25610 assigned tothe Assignee of the present U.S. application. The Japanese documentdiscloses a BP measuring apparatus which measures a BP value of a livingsubject according to the oscillometric BP measuring method, i.e.,prescribed software algorithm. The BP measuring apparatus has a displaydevice which displays a series of wave amplitudes in a two-dimensionalgraph having a first axis indicative of the cuff pressure and a secondaxis indicative of the wave amplitude. A medical worker such as a doctorcan easily recognize, from the distribution of the wave amplitudes withrespect to the cuff pressure, the amounts of error of the BP measurementdue to external causes such as the physical motion of the subject andthe noise produced from peripheral devices. Thus, the doctor can judgewhether the conditions of the BP measurement are proper or appropriate.A series of wave amplitudes displayed in the two-dimensional areaprovided on the display device may define a complex envelope changeabledepending upon external factors. There have been employed varioussmoothening techniques each of which is used to smoothen the envelope ofthe wave amplitudes obtained in carrying out a BP measurement. The BPmeasuring method disclosed in Non-Examined Japanese Patent Applicationlaid open for inspection under Publication No. 63(1988)-51837 is one ofthe smoothening techniques. In this method, an odd number of successiveamplitudes are selected from the series of amplitudes, and the amplitudepositioned at the center of the selected amplitudes is replaced with theamplitude having the median magnitude. This is the so-called medicalfilter. By sequentially repeating this median-filter treatment with allthe amplitudes by removing the oldest one of the odd number ofamplitudes and adding the following amplitude, the envelope of theamplitudes is smoothened. Since a BP measurement is carried out based onthe thus smoothened envelope of the amplitudes, the accuracy ofmeasurement of BP values is increased. Although a series of amplitudesare displayed as a two-dimensional graph on the display device, theamplitudes defines only a smoothened envelope wherein the errors ofamplitudes due to external factors have been corrected. From asmoothened envelope, a doctor cannot judge whether the conditions ofmeasurement of BP values are proper, unlike a non-smoothened envelopeshowing the distribution of non-treated "raw" amplitudes from which thedoctor can judge.

SUMMARY OF THE INVENTION

It is a first object of the present invention to provide a bloodpressure measuring apparatus which enables a patient or a doctor torecognize the time change of the waveforms of pulse waves of the patientand judge whether the patient has a heart disease, when a BP value orvalues is/are measured on the patient.

The first object has been achieved by the present invention. Accordingto a first aspect of the present invention, there is provided anapparatus for measuring a blood pressure of a living subject,comprising: a blood pressure measuring device which measures a bloodpressure value of the subject; a first memory which stores a pluralityof blood pressure values measured by the blood pressure measuringdevice, in an order of measurement of the blood pressure values; a pulsewave detecting device which detects a pulse wave produced from anarterial vessel of the subject in synchronism with heartbeat of thesubject while each of the blood pressure values is measured by the bloodpressure measuring device; a second memory which stores a waveform ofthe pulse wave detected by the pulse wave detecting device, in theorder, the second memory storing the respective waveforms of the pulsewaves each of which is detected by the pulse wave detecting device whilea corresponding one of the blood pressure values is measured by theblood pressure measuring device; and an output device which outputs theblood pressure values stored in the first memory, in the order, and aplurality of curves respectively representing the waveforms stored inthe second memory, in the order, in a side-by-side relation with eachother.

In the BP measuring apparatus in accordance with the first aspect of theinvention, the output device outputs the BP values stored in the firstmemory, in the order of measurement of those BP values, and a pluralityof curves representing the waveforms stored in the second memory, in thesame order, in a side-by-side relation with each other. The outputdevice may operate in this manner, when the BP apparatus operates formeasuring a BP value or values of a living subject such as a patient.Since the BP apparatus is easily used, the patient or a medical workercan easily recognize the time change of the waveforms of the pulse wavesof the patient together with the time change of the BP values of thepatient. Therefore, the patient or the medical worker can make adiagnosis that the patient may have a heart disease.

In a preferred embodiment in accordance with the first aspect of theinvention, the blood pressure measuring device comprises an inflatablecuff adapted to be wound around a body portion of the subject, and thepulse wave detecting device comprises a sensor which detects, as thepulse wave, a pressure oscillation produced in the cuff in synchronismwith heartbeat of the subject. In this embodiment, the sensor used aspart of the blood pressure measuring device is also used to detect thepulse wave of the patient. Since an exclusive pulse-wave sensor is notneeded, the BP apparatus enjoys a simple construction and a lowmanufacturing cost.

In another embodiment in accordance with the first aspect of theinvention, the BP measuring apparatus further comprises amplitudemodifying means for modifying an amplitude of each of the waveformsdetected by the pulse wave detecting device, so that the waveformsoutput by the output device have a prescribed amplitude. In thisembodiment, the patient or the doctor can easily compare the waveformsof the pulse waves with each other, so that the patient or the doctorcan correctly recognize the time change of the waveforms. In this case,the BP measuring apparatus may further comprise wavelength modifyingmeans for modifying a wavelength of the each of the waveforms detectedby the pulse wave detecting device, so that the waveforms output by theoutput device have a prescribed wavelength.

In yet another embodiment in accordance with the first aspect of theinvention, the BP measuring apparatus further comprises: evaluatingmeans for evaluating a characteristic of each of the waveforms detectedby the pulse wave detecting device, and providing an evaluated value ofthe each waveform; and a third memory which stores the evaluated valueof the each waveform, in the order, wherein the output device outputsthe evaluated values stored in the third memory, in the order. In thisembodiment, the patient or the doctor can quantitatively figure out thechange of the pulse waves, so that the patient or the doctor can moreeasily recognize the time change of the waveforms of the pulse waves.

In another embodiment in accordance with the first aspect of theinvention, the output device comprises means for outputting a firstgraphical representation indicating the blood pressure values stored inthe first memory, and a second graphical representation indicating theevaluated values stored in the third memory, along a common axisindicative of time, and outputting the curves representing the waveformsstored in the second memory, along the common axis. In this embodiment,the BP values, and the evaluated values of the waveforms of the pulsewaves are output together with the curves of waveforms along a common"time" axis. The patient or the doctor can more easily recognize thetime change of the waveforms.

It is a second object of the present invention to provide an automaticblood pressure measuring apparatus which enables a living body orsubject to have a strong visual impression that he or she has a bloodpressure abnormality.

The second object has been achieved according to a second aspect of thepresent invention, which provides an apparatus for measuring a bloodpressure of a living subject, comprising: a blood pressure measuringdevice which measures a blood pressure value of the subject; a firstmemory which accumulatively stores a plurality of blood pressure valuesmeasured by the blood pressure measuring device; a second memory whichstores a plurality of pictorial images each of which indicates acorresponding one of a plurality of different evaluations of the bloodpressure of the subject; image selecting means for selecting one of thepictorial images which corresponds to a current blood pressure value ofthe subject measured by the blood pressure measuring device; and anoutput device which outputs the one pictorial image selected by theimage selecting means, together with the blood pressure values stored inthe first memory.

In the BP measuring apparatus in accordance with the second aspect ofthe invention, the output device outputs a pictorial image selected bythe image selecting means, together with the BP values stored in thefirst memory. The pictorial image selected by the image selecting meanscorresponds to a current BP value of the subject measured by the bloodpressure measuring device. Thus, the subject can have a strong visualimpression that his or her blood pressure is abnormal, and can keep itin mind for a long time.

In a preferred embodiment in accordance with the second aspect of theinvention, the second memory stores a plurality of groups of pictorialimages each image of which indicates a corresponding one of a pluralityof different evaluations of the blood pressure of the subject, andwherein the apparatus further comprises: a data obtaining device whichobtains identification data identifying the subject; and group selectingmeans for selecting one of the groups of pictorial images whichcorresponds to the identification data obtained by the data obtainingdevice, so that the image selecting means selects the one pictorialimage from the selected group of pictorial images. In this embodiment,the group selecting means may be adapted to select a group of pictorialimages based on the identification data including the personalinformation of the subject, such as sex, age, and clinical history.Thus, the image selecting means selects a pictorial image whichaccurately corresponds to a current BP value of the subject measured bythe blood pressure measuring device.

In another embodiment in accordance with the second aspect of theinvention, the output device comprises a printer which outputs, on arecording sheet, the one pictorial image selected by the image selectingmeans, together with the blood pressure values stored in the firstmemory. In this embodiment, the subject can bring the recording sheet onwhich the selected pictorial image is recorded. Thus, the subject is notrequired to write down the measured BP values or keep them in mind.

In yet another embodiment in accordance with the second aspect of theinvention, the output device comprises means for outputting a graphicrepresentation indicating a time change of the blood pressure valuesstored in the first memory. In this embodiment, the subject can easilyrecognize the time change of the BP values.

It is a third object of the present invention to provide an automaticblood pressure measuring apparatus which is easily operable forproducing a pictorial image.

The third object has been achieved according to a third aspect of thepresent invention, which provides an apparatus for measuring a bloodpressure of a living subject, comprising: a blood pressure measuringdevice which measures a blood pressure value of the subject; a firstmemory which accumulatively stores a plurality of blood pressure valuesmeasured by the blood pressure measuring device; a second memory whichstores at least one pictorial image; an output device which outputs thepictorial image stored in the second memory, together with the bloodpressure values stored in the first memory; an image reading devicewhich reads an original image from an original; an editing device whichis operable for editing the original image read by the image readingdevice; and a registering device which registers the image edited by theediting device, by storing the edited image as the pictorial image inthe second memory.

In the BP measuring apparatus in accordance with the third aspect of theinvention, the image reading device reads an original image from anoriginal, the editing device is operable for editing the original image,and the registering device registers the edited image, by storing it inthe second memory. The output device outputs the edited image, i.e.,pictorial image together with the BP values stored in the first memory.The pictorial image accompanying the BP values enable the subject tokeep the BP values in mind. In addition, the pictorial image is easilyprepared and registered in the present BP measuring apparatus.

In a preferred embodiment in accordance with the third aspect of theinvention, the second memory stores a plurality of pictorial images eachof which is related to a time of measurement of the blood pressure ofthe subject, and wherein the apparatus further comprises: a clock devicewhich produces a signal indicative of a time when the blood pressuremeasuring device measures a blood pressure value of the subject; andimage selecting means for selecting one of the pictorial images whichcorresponds to a time of measurement of a current blood pressure valueof the subject measured by the blood pressure measuring device, so thatthe output device outputs the selected one pictorial image together withthe blood pressure values stored in the first memory. In thisembodiment, the second memory may be adapted to store pictorial imageseach related to the date and time of measurement of a BP value of thesubject, for example, pictorial images representing flowers at fourseasons, landscapes at four seasons, etc. The pictorial imageaccompanying the measured BP values gives a strong visual impression tothe subject, so that the subject can keep the BP values in mind.

In another embodiment in accordance with the third aspect of theinvention, the second memory stores a plurality of random selectablepictorial images, and wherein the apparatus further comprises: a randomvalue generator which provides, according to a random function, a randomvalue in response to an operation of the blood pressure measuringdevice; and image selecting means for selecting one of the pictorialimages which corresponds to a random value produced by the random valuegenerator, so that the output device outputs the selected one pictorialimage together with the blood pressure values stored in the firstmemory. In this embodiment, in different BP measurements, differentpictorial images may be output together with the BP values of thesubject. The different pictorial images help the subject to keep the BPvalues in mind.

It is a fourth object of the present invention to provide an automaticblood pressure measuring apparatus which provides information related toa medicine to be given to a patient, thereby enabling a medical workerto omit the directions for use of the medicine.

The fourth object has been achieved according to a fourth aspect of thepresent invention, which provides an apparatus for measuring a bloodpressure of a living subject, comprising: a blood pressure measuringdevice which measures a blood pressure value of the subject; a firstmemory which accumulatively stores a plurality of blood pressure valuesmeasured by the blood pressure measuring device; a second memory whichstores a plurality of batches of medicine-related information each ofwhich is related to a corresponding one of a plurality of medicinesadministrable in treating the blood pressure of the subject; an inputdevice which is operable for specifying one of the medicines; and anoutput device which selects, from the second memory, one of the batchesof medicine-related information which corresponds to the one medicinespecified by the input device, and outputs the selected batch ofmedicine-related information, together with the blood pressure valuesstored in the first memory.

In the BP measuring apparatus in accordance with the fourth aspect ofthe invention, the output device selects, from the second memory, one ofthe batches of medicine-related information which corresponds to the onemedicine specified by the input device, and outputs the selected batchof medicine-related information, together with the blood pressure valuesstored in the first memory. In the case where a doctor gives aBP-treating medicine to a patient after having made a diagnosis based onthe measured BP values of the patient, the doctor is just required tospecify the medicine through the input device, so that the output deviceoutputs, together with the BP values of the patient, the batch ofinformation related to the medicine, the information including thedirections for use of the medicine, the objects of administration of thesame, and other necessary items. Thus, the doctor is not required toprovide any explanation to the patient.

It is a fifth object of the present invention to provide an apparatusfor automatically winding an arm belt around an upper arm of a livingsubject, in measuring a blood pressure of the subject, wherein theapparatus permits the subject to keep his or her natural posture andensures that the measurement of BP values is carried out with accuracy.

The fifth object has been achieved according to a fifth aspect of thepresent invention, which provides an apparatus for winding an arm beltincluding an inflatable bag, around an upper arm of a living subject, inmeasuring a blood pressure of the subject, a pressurized air beingsupplied to the bag to inflate the bag and thereby press the upper arm,the apparatus comprising: an arm receiver inside which the arm belt isprovided so as to define a substantially cylindrical space into whichthe upper arm of the subject is inserted from one of opposite ends ofthe cylindrical space; a positioning device which changes a position ofthe arm receiver relative to the upper arm of the subject; a detectorwhich detects a misalignment of a central axis line of the cylindricalspace of the arm receiver from a longitudinal axis line of the upper armof the subject; and a control device which controls, based on themisalignment detected by the detector, the positioning device to changethe position of the arm receiver relative to the upper arm so that thecentral axis line of the cylindrical space of the arm receiver issubstantially aligned with the longitudinal axis line of the upper arm.

In the arm-belt winding apparatus in accordance with the fifth aspect ofthe invention, when the subject inserts his or her upper arm into thearm receiver, the detector detects the misalignment of the central axisline of the arm receiver from the longitudinal axis line of the upperarm of the subject, and the control device controls, based on themisalignment detected by the detector, the positioning device to changethe position of the arm receiver relative to the upper arm so that thecentral axis line of the arm receiver is substantially aligned with thelongitudinal axis line of the upper arm. Thus, the present apparatusensures that the upper arm is suitably inserted such that the arteriesof the upper arm are not locally or partially pressed by the belt,without requiring the subject to change his or her posture. That is, thepresent apparatus ensures that the measurement of BP values is effectedwith accuracy, permitting the subject to keep his or her naturalposture.

It is a sixth object of the present invention to provide a BP monitoringapparatus which monitor the blood pressure of a living subject with highreliability and without giving any burden on the subject.

The sixth object has been achieved according to a sixth aspect of thepresent invention, which provides an apparatus for monitoring a bloodpressure of a living subject, comprising: an inflatable cuff adapted tobe wound around a body portion of the subject, the cuff being inflatedto provide a pressure to press the body portion; a detector whichdetects a plurality of pulse amplitudes produced in the cuff beinginflated to press the body portion; a pressure changing device whichincreases the pressure of the cuff to a prescribed value lower than amean blood pressure of the subject, and subsequently decreases the cuffpressure from the prescribed value, in each of a plurality of periodiccycles; rate-of-change determining means for determining, with respectto the cuff pressure, a rate of change of the pulse amplitudes detectedby the detector while the cuff pressure is changed by the pressurechanging device; and first abnormality judging means for judging, basedon the determined rate of change, whether the blood pressure of thesubject is abnormal.

In the blood pressure monitoring apparatus in accordance with the sixthaspect of the invention, the rate-of-change determining meansdetermines, with respect to the cuff pressure, a rate of change of thepulse amplitudes detected by the detector while the cuff pressure ischanged by the pressure changing device, and the first abnormalityjudging means judges, based on the determined rate of change, whetherthe blood pressure of the subject is abnormal. The BP monitoring of thepresent apparatus is carried out on the discovery that the rate ofchange of a low-pressure-side portion of the envelope of the pulseamplitudes with respect to the cuff pressure changes as the bloodpressure of the subject changes. Therefore, the reliability of the BPmonitoring is improved so much. In addition, since the rate of change ofthe pulse amplitudes is obtained while the cuff pressure is changed in alow-pressure range between atmospheric pressure and the prescribed lowpressure, the subject is free of the burden.

In a preferred embodiment in accordance with the sixth aspect of theinvention, the monitoring apparatus further comprises a blood pressuremeasuring device which automatically measures a blood pressure value ofthe subject in a series of prescribed steps when the first abnormalityjudging means judges that the blood pressure of the subject is abnormal.In this embodiment, the BP value of the subject just at the time offinding of the blood pressure abnormality is obtained by the bloodpressure measuring device. The thus obtained BP value is clinicallyimportant, so that a medical worker such as a doctor can make anappropriate treatment on the subject such as a patient.

In another embodiment in accordance with the sixth aspect of theinvention, the first abnormality judging means comprises means forjudging whether a pulse amplitude detected by the detector while thecuff pressure is changed by the pressure changing device, is smallerthan a reference value, the first abnormality judging means judging thatthe blood pressure of the subject is abnormal, when the pulse amplitudeis smaller than the reference value. Since the envelope of pulseamplitudes obtained from people suffering from low blood pressurebecause of being in a shock state, is more or less flat with respect tothe cuff pressure, it is considerably difficult to identify anabnormally low blood pressure based on the rate of change of the pulseamplitudes with respect to the cuff pressure. In this embodiment,however, since a pulse amplitude is compared with a reference value toidentify the blood pressure abnormality, the reliability ofidentification of the subject's shock state is improved.

In yet another embodiment in accordance with the sixth aspect of theinvention, the pressure changing device comprises means for holding thecuff pressure at the prescribed value for a prescribed period of time,and the apparatus further comprises second abnormality judging means forjudging, based on a pulse amplitude detected by the detector during theprescribed period, whether the blood pressure of the subject isabnormal. Since the two sorts of abnormality judging means are employedin the present BP monitoring apparatus, the reliability of the BPmonitoring is much more improved.

In another embodiment in accordance with the sixth aspect of theinvention, the pressure changing device comprises means for increasingand holding the cuff pressure to and at a first prescribed value, andsubsequently increasing and holding the cuff pressure to and at a secondprescribed value higher than the first prescribed value, and therate-of-change determining means comprises means for determining, withrespect to the cuff pressure, a rate of change of a pulse amplitudedetected by the detector when the cuff pressure is held at the secondprescribed value from a pulse amplitude detected by the detector whenthe cuff pressure is held at the first prescribed value. In thisembodiment, the rate-of-change determining means determines, withaccuracy, the rate of change of a low-pressure-side increasing portionof the envelope of the pulse amplitudes, based on the respective pulseamplitudes detected at the first and second cuff-pressure values. Thus,the reliability of the BP monitoring of the present apparatus isimproved. In this case, the rate-of-change determining means may beadapted such that, if at least two successive pulses havingsubstantially the same pulse amplitude are detected while the cuffpressure is held at each of the first and second values, the determiningmeans employs that pulse amplitude in determining the rate of change ofthe pulse amplitudes. Since in this modified manner "noise" pulses areremoved from true pulses, the reliability of the BP monitoring is stillmore improved.

In another embodiment in accordance with the sixth aspect of theinvention, the monitoring apparatus further comprises second abnormalityjudging means for judging whether the blood pressure of the subject isabnormal, based on a pulse amplitude detected by the detector when thecuff pressure is held at the second prescribed value. In thisembodiment, it is not necessary to provide an exclusive cuff-pressureholding period during which to detect a pulse amplitude to be used bythe second abnormality judging means for judging whether the subject hasblood pressure abnormality.

In another embodiment in accordance with the sixth aspect of theinvention, the monitoring apparatus further comprises a blood pressuremeasuring device which automatically measures a blood pressure value ofthe subject in a series of prescribed steps when at least one of thefirst and second abnormality judging means judges that the bloodpressure of the subject is abnormal. In this embodiment, when at leastone of the first and second abnormality judging means judges that theblood pressure of the subject is abnormal, the blood pressure measuringdevice automatically measures a blood pressure value of the subject.Thus, the reliability of the BP monitoring is improved so much.

In another embodiment in accordance with the sixth aspect of theinvention, the first abnormality judging means comprises means forjudging whether the determined rate of change is greater than areference value, the first abnormality judging means judging that theblood pressure of the subject is abnormal when the determined rate ofchange is greater than the reference value, and the apparatus furthercomprises: an input device which is operable for inputting a desiredvalue as the reference value; and changing means for changing, based onthe input value as the reference value, the prescribed value to a newvalue to which the cuff pressure is increased by the pressure changingdevice. In this embodiment, the cuff pressure applied to the livingsubject such as a patient is reduced to as low as possible a value.

It is a seventh object of the present invention to provide an automaticblood pressure measuring apparatus which has the function of estimatinga BP value of a living subject before an actual BP value of the subjectis measured during the decreasing of the cuff pressure.

The seventh object has been achieved by the present invention. Accordingto a seventh aspect of the invention, there is provided an apparatus forautomatically measuring a blood pressure of a living subject,comprising: an inflatable cuff adapted to be wound around a body portionof the subject, the cuff being inflated to provide a cuff pressure topress the body portion; a pressure sensor which detects the cuffpressure; a pressure changing device which changes the cuff pressure; ablood pressure measuring device which measures a blood pressure value ofthe subject by reading the cuff pressure detected by the pressure sensorwhile the cuff pressure is decreased at a prescribed rate by thepressure changing device; a waveform detector which detects a waveformof a pulse wave produced in the cuff during the decreasing of the cuffpressure, the waveform of the pulse wave being changeable with the cuffpressure; determining means for determining a relationship between (A)evaluated values of a waveform of a pulse wave, (B) pressure values ofthe cuff, and (C) blood pressure values of the subject, based on (a) anevaluated value of the waveform of the pulse wave detected by thewaveform detector, (b) a pressure value of the cuff at a time ofdetection of the waveform by the waveform detector, and (c) the bloodpressure value of the subject measured by the blood pressure measuringdevice, the relationship being proper to the subject; and estimatingmeans for estimating, according to the determined relationship, a bloodpressure value of the subject based on (a') an evaluated value of awaveform of a pulse wave detected by the waveform detector while thecuff pressure is increased before the cuff pressure is decreased at theprescribed rate in measuring an actual blood pressure of the subject and(b') a pressure value of the cuff at a time of detection of the waveformduring the increasing of the cuff pressure.

In the automatic BP measuring apparatus in accordance with the seventhaspect of the invention, the estimating means estimates, according tothe determined relationship, a BP value of the subject based on (a') anevaluated value of the waveform of at least one pulse of a pulse wavedetected by the waveform detector while the cuff pressure is increasedbefore the cuff pressure is decreased and (b') a pressure value of thecuff at the time of detection of the waveform during the increasing ofthe cuff pressure. Thus, the present apparatus quickly gives a doctor anestimated BP value of the subject, even though the estimated value maybe some or less rough.

In a preferred embodiment in accordance with the seventh aspect of thepresent invention, the BP measuring apparatus further comprisesevaluating means for evaluating a plurality of characteristics of thewaveform of the pulse wave detected by the waveform detector during thedecreasing of the cuff pressure, and providing an evaluated value ofeach of the waveform characteristics, and the determining meansdetermines a plurality of relationships each based on the evaluatedvalue of a corresponding one of the waveform characteristics and theestimating means calculates a plurality of blood pressure values of thesubject according to the determined relationships, respectively, andestimates the blood pressure value of the subject based on thecalculated blood pressure values. In this embodiment, since theestimated BP value of the subject is provided based on a variety of BPvalues determined according to a plurality of sorts of relationships,the reliability of the estimated BP value is increased. The waveformcharacteristics may comprise at least two selected from the pulseamplitude, Amp-b; the maximum slope of the increasing portion of thewaveform, SLOPE; the degree of sharpness of the waveform, % MAP; thepercentage of the increasing portion of the waveform to the cyclicperiod thereof, % IPP; and the percentage of the time difference betweenthe primary and secondary peaks of the waveform to the cyclic periodthereof, PI (peak index).

In another embodiment in accordance with the seventh aspect of thepresent invention, the BP measuring apparatus further comprises targetpressure determining means for determining, based on the estimated bloodpressure value of the subject, a target pressure value to which the cuffpressure is increased, and the pressure changing device startsdecreasing the cuff pressure after the cuff pressure is increased to thetarget pressure. In this embodiment, the cuff pressure is increased upto the target pressure that may be higher by a prescribed value than anestimated systolic BP value of the subject. Therefore, the cuff pressureis by no means increased up to an unnecessarily high pressure relativeto the systolic BP value of the subject, or is by no means re-increasedto another target pressure higher than the first or initial targetpressure when the first target pressure is not sufficiently high. Thus,the burden to the subject is reduced as such.

In another embodiment in accordance with the seventh aspect of thepresent invention, the BP measuring apparatus further comprises:abnormality identifying means for identifying a blood pressureabnormality of the subject by comparing the estimated blood pressurevalue of the subject with a reference value; and an output device whichoutputs, when the blood pressure abnormality of the subject isidentified, information indicative of the identification of the bloodpressure abnormality of the subject. In this embodiment, the outputdevice informs a doctor of whether the blood pressure the subject isabnormal, at an early stage when the cuff pressure is increased beforebeing decreased. Thus, the doctor can make a quick decision on whetherto give a medical treatment to the subject.

According to an eighth aspect of the present invention, there isprovided an apparatus for automatically measuring a blood pressure of aliving subject, comprising: an inflatable cuff adapted to be woundaround a body portion of the subject, the cuff being inflated to providea cuff pressure to press the body portion; a pressure sensor whichdetects the cuff pressure; a pressure changing device which changes thecuff pressure; a blood pressure measuring device which measures a bloodpressure value of the subject by reading the cuff pressure detected bythe pressure sensor while the cuff pressure is decreased at a prescribedrate by the pressure changing device; a waveform detector which detectsa waveform of a pulse wave produced in the cuff during the decreasing ofthe cuff pressure, the waveform of the pulse wave being changeable withthe cuff pressure; a memory which stores a pulse amplitude of the pulsewave detected by the waveform detector, and a pressure value of the cuffat a time of detection of the pulse amplitude; determining means fordetermining an envelope representing a relationship between (a) aplurality of pulse amplitudes detected by the waveform detector whilethe cuff pressure is increased before the cuff pressure is decreased atthe prescribed rate and (b) a plurality of pressure values of the cuffat respective times of detection of the pulse amplitudes; and estimatingmeans for estimating a blood pressure value of the subject, based on thedetermined envelope, according to a prescribed relationship.

In the automatic BP measuring apparatus in accordance with the eighthaspect of the invention, the estimating means estimates a BP value ofthe subject, based on the determined envelope, according to a prescribedrelationship between blood pressure and a shape-related characteristicof an envelope. The prescribed relationship is, e.g., such that twocuff-pressure values respectively corresponding to two points on theenvelope at which the amplitudes of the envelope significantly largelychange, are estimated as the systolic and diastolic BP values of thesubject, like the relationship employed in the oscillometric BPdetermining method. The present apparatus provides a doctor with theestimated BP value of the subject, based on the envelope obtained duringthe increasing of the cuff pressure before the decreasing of the same.Thus, the doctor quickly obtains an estimated BP value of a patient,even if the estimated value may be some or less rough.

It is an eighth object of the present invention to provide a bloodpressure measuring apparatus which determines a blood pressure value ofa living subject based on a series of smoothened wave amplitudes andwhich enables a medical worker to easily judge whether the condition ofmeasurement of BP values is proper or not.

The eight object has been achieved by the present invention. Accordingto a ninth aspect of the invention, there is provided an apparatus formeasuring a blood pressure of a living subject, comprising: aninflatable cuff adapted to be wound around a body portion of thesubject, the cuff being inflated to provide a cuff pressure to press thebody portion; a pressure changing device which changes the cuffpressure; a blood pressure measuring device which (a) obtains aheartbeat-synchronous signal wave generated from arteries of the bodyportion in synchronism with heartbeat of the subject while the cuffpressure is changed by the pressure changing device, (b) determinesrespective amplitudes of a plurality of successive pulses of theheartbeat-synchronous signal wave each of which corresponds to one cycleof heartbeat of the subject, and provides, as a first series ofdetermined pulse amplitudes, the determined pulse amplitudes arranged inan order of generation of the corresponding pulses, (c) smoothens thefirst series of determined pulse amplitudes and thereby provides asecond series of smoothened pulse amplitudes, and (d) determines a bloodpressure value of the subject based on a change in the second series ofsmoothened pulse amplitudes; an output device which outputs atwo-dimensional representation comprising a number of picture elements;and a control device which controls the output device to output thetwo-dimensional representation containing the first series of determinedpulse amplitudes and the second series of smoothened pulse amplitudessuch that one of the first and second series of pulse amplitudes aresuperimposed on the other series of pulse amplitudes.

In the BP measuring apparatus in accordance with the ninth aspect of theinvention, the output device outputs the two-dimensional representationcontaining the first series of determined pulse amplitudes and thesecond series of smoothened pulse amplitudes such that one of the firstand second series of pulse amplitudes are superimposed on the otherseries of pulse amplitudes. Therefore, a medical worker such a doctorcan visually recognize the differences between the first and secondseries of pulse amplitudes in the two-dimensional representation. Thosedifferences result from external factors such as the physical motion ofthe subject or the noise generated from peripheral devices. Based on thetotal amount of the differences and the respective positions of thedifferences with respect to the cuff pressure, the doctor can easilyjudge whether the measured BP value contains a great error due to theexternal factors, i.e., whether the condition of measurement of the BPvalue is proper.

According to a tenth aspect of the present invention, there is providedan apparatus for measuring a blood pressure of a living subject,comprising: an inflatable cuff adapted to be wound around a body portionof the subject, the cuff being inflated to provide a cuff pressure topress the body portion; a pressure changing device which changes thecuff pressure; a blood pressure measuring device which (a) obtains aheartbeat-synchronous signal wave generated from arteries of the bodyportion in synchronism with heartbeat of the subject while the cuffpressure is changed by the pressure changing device, (b) determinesrespective amplitudes of a plurality of successive pulses of theheartbeat-synchronous signal wave each of which corresponds to one cycleof heartbeat of the subject, and provides, as a first series ofdetermined pulse amplitudes, the determined pulse amplitudes arranged inan order of generation of the corresponding pulses, (c) smoothens thefirst series of determined pulse amplitudes and thereby provides asecond series of smoothened pulse amplitudes, and (d) determines a bloodpressure value of the subject based on a change in the second series ofsmoothened pulse amplitudes; an output device which outputs a degree ofpropriety of a measurement condition under which the blood pressurevalue of the subject is determined by the blood pressure measuringdevice; calculating means for calculating a degree of correction of thesecond series of smoothened pulse amplitudes from the first series ofdetermined pulse amplitudes, by calculating a ratio of (a) respectivedifferences between (a1) the determined pulse amplitudes correspondingto respective pressure values of the cuff within a prescribed pressurerange and (a2) the corresponding smoothened pulse amplitudes, to (b) atleast one of the determined pulse amplitudes and the correspondingsmoothened pulse amplitudes; and a control device which controls theoutput device to output the degree of propriety of the measurementcondition which corresponds to the degree of correction of the secondseries of pulse amplitudes calculated by the calculating means.

In the BP measuring apparatus in accordance with the tenth aspect of theinvention, the output device outputs the degree of propriety of themeasurement condition which corresponds to the degree of correction ofthe second series of pulse amplitudes calculated by the calculatingmeans. Thus, a medical worker can visually recognize the degree ofpropriety of the condition of BP measurement. By comparing the degree ofcorrection reflecting the amount of external factors, with a prescribedreference value, the present apparatus may automatically judge whetherthe measured BP value contains a great error due to the externalfactors, i.e., whether the condition of measurement of the BP value isproper.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and optional objects, features, and advantages of the presentinvention will be better understood by reading the following detaileddescription of the preferred embodiments of the invention whenconsidered in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a blood pressure (BP) measuringapparatus embodying the present invention;

FIG. 2 is a diagrammatic view of the electric arrangement of theapparatus of FIG. 1;

FIG. 3 is a flow chart representing a control program according to whichthe apparatus of FIG. 1 operates;

FIG. 4 is a view illustrating an evaluated value, % MAP, representing acharacteristic of the waveform of pulse wave, the value % MAP beingdetermined at Step S8 of FIG. 3;

FIG. 5 is a view of a printed output of the apparatus of FIG. 1 as aresult of an operation of the same according to the flow chart of FIG.3;

FIG. 6 is a view of a printed output of another BP measuring apparatusobtained by modifying the apparatus of FIG. 1;

FIG. 7 is a view of a printed output of yet another BP measuringapparatus obtained by modifying the apparatus of FIG. 1;

FIG. 8 is a diagrammatic view corresponding to FIG. 2, showing theelectric arrangement of a BP measuring apparatus as a second embodimentof the present invention;

FIG. 9 is a flow chart representing a control program according to whichthe apparatus of FIG. 8 operates in a BP evaluation mode;

FIG. 10 is a view corresponding to FIG. 5, showing a printed output ofthe apparatus of FIG. 8 as a result of an operation of the sameaccording to the flow chart of FIG. 9, in the case where measured BPvalues are normal;

FIG. 11 is a view corresponding to FIG. 10, showing another printedoutput of the apparatus of FIG. 8, in the case where measured BP valuesare somewhat abnormal;

FIG. 12 is a view corresponding to FIG. 10, showing yet another printedoutput of the apparatus of FIG. 8, in the case where measured BP valuesare abnormal;

FIG. 13 is a flow chart corresponding to FIG. 9, representing anothercontrol program according to which the apparatus of FIG. 8 operates;

FIG. 14 is a flow chart corresponding to FIG. 9, representing yetanother control program according to which the apparatus of FIG. 8operates;

FIG. 15 is a flow chart corresponding to FIG. 9, representing anothercontrol program according to which the apparatus of FIG. 8 operateseither in a random image output mode or in a time-related image outputmode;

FIG. 16 is a flow chart corresponding to FIG. 9, representing yetanother control program according to which the apparatus of FIG. 8operates in an image/comment edit mode;

FIG. 17 is a side view of a BP measuring apparatus as a third embodimentof the present invention;

FIG. 18 is a diagrammatic view of a partly structural and partlyelectric arrangement of the apparatus of FIG. 17, showing anarm-receiver positioning device and a misalignment detector;

FIG. 19 is a view of a cylinder drive device of the apparatus of FIG.17;

FIG. 20 is a view of another arm-receiver positioning device which maybe employed in the apparatus of FIG. 17;

FIG. 21(A) is a front view of another misalignment detector which may beemployed in the apparatus of FIG. 17;

FIG. 21(B) is a cross section of the misalignment detector of FIG. 21(A)taken along Line 21(B)--21(B);

FIG. 22 is a view of yet another arm-receiver positioning device and yetanother misalignment detector which may be employed in the apparatus ofFIG. 17;

FIG. 23 is a diagrammatic view of a BP monitor apparatus as a fourthembodiment of the present invention;

FIG. 24 is a flow chart representing a first half of a control programaccording to which the apparatus of FIG. 23 operates;

FIG. 25 is a flow chart representing a second half of the controlprogram of FIG. 24;

FIG. 26 is a view showing a linear function defining a relationshipbetween pulse amplitude and blood pressure, the function beingdetermined in a step of the flow chart of FIG. 24;

FIG. 27 is a time chart representing the time change of cuff pressureP_(c) when the monitor apparatus of FIG. 23 operates according to theflow charts of FIGS. 24 and 25;

FIG. 28 is a view explaining a manner in which a rate of change θ ofpulse amplitudes A_(m) with respect to cuff pressures P_(c) iscalculated in a step of the flow chart of FIG. 25;

FIG. 29 is a view showing the respective envelopes of pulse amplitudesof a living subject having a normal blood pressure, a subject sufferingan abnormally low blood pressure, and a subject being in a shock state;

FIG. 30 is a flow chart representing steps which may be carried out inplace of Step S117 of FIG. 25 by the monitor apparatus of FIG. 23;

FIG. 31 is a time chart representing the time change of cuff pressureP_(c) when the monitor apparatus of FIG. 23 operates according to theflow chart of FIG. 30;

FIG. 32 is a flow chart representing steps which may be carried out inaddition to the steps of FIGS. 24 and 25 by the monitor apparatus ofFIG. 23;

FIG. 33 is a view showing a relationship which is utilized in a step ofthe flow chart of FIG. 32;

FIG. 34 is a diagrammatic view of a BP measuring apparatus as a fifthembodiment of the present invention;

FIG. 35(A) is a view showing an example of a pulse waveform obtainedfrom a cuff wound around a body portion of a living subject when thecuff pressure is taking a value around a systolic blood pressure of thesubject;

FIG. 35(B) is a view showing a pulse waveform obtained from the cuffwhen the cuff pressure is taking a value around a mean blood pressure ofthe subject;

FIG. 35(C) is a view showing a pulse waveform obtained from the cuffwhen the cuff pressure is taking a value around a diastolic bloodpressure of the subject;

FIG. 36 is a flow chart representing a first half of a control programaccording to which the apparatus of FIG. 34 operates;

FIG. 37 is a flow chart representing a second half of the controlprogram of FIG. 36;

FIG. 38 is a time chart representing the change of cuff pressure P_(c)in a BP measurement and the change of pulse amplitudes in relation withthe change of cuff pressure P_(c) ;

FIG. 39 is a view explaining the respective definitions of variouswaveform characteristics determined by the apparatus of FIG. 34 toevaluate a pulse waveform;

FIG. 40 is a view explaining a relationship between blood pressure(i.e., cuff pressure values P_(c) as the measured blood pressure values)and each of the waveform characteristics;

FIG. 41 is a view explaining a relationship between cuff pressure P_(c)and pulse amplitude Amp-b;

FIG. 42 is a view explaining a relationship between cuff pressure P_(c)and waveform slope SLOPE;

FIG. 43 is a view explaining a relationship between cuff pressure P_(c)and evaluated value % MAP;

FIG. 44 is a view explaining a relationship between cuff pressure P_(c)and evaluated value % IPP;

FIG. 45 is a view explaining a relationship between cuff pressure P_(c)and evaluated value PI;

FIG. 46 is a flow chart representing a first half of a modified controlprogram according to which the apparatus of FIG. 34 operates;

FIG. 47 is a time chart representing a second half of the modifiedcontrol program of FIG. 46;

FIG. 48 is a view explaining a first envelope H₁ representing arelationship between cuff pressure values P_(c) and pulse amplitudes PA,the pulse amplitudes being obtained while the cuff pressure P_(c) isslowly decreased according to the flow chart of FIG. 46;

FIG. 49(A) is a view explaining a first example of a second envelope H₂representing a relationship between cuff pressure values P_(c) and pulseamplitudes PA, the pulse amplitudes being obtained while the cuffpressure P_(c) is quickly increased according to the flow chart of FIG.47;

FIG. 49(B) is a view explaining a second example of the second envelopeH₂ ;

FIG. 49(C) is a view explaining a third example of the second envelopeH₂ ;

FIG. 49(C) is a view explaining a fourth example of the second envelopeH₂ ;

FIG. 50 is a diagrammatic view of an automatic BP measuring apparatus asa sixth embodiment of the present invention;

FIG. 51 is a flow chart representing a control program according towhich the apparatus of FIG. 50 operates;

FIG. 52 is a flow chart representing the steps carried out in thesubroutine of Step S305 of FIG. 51;

FIG. 53 is a view of an example of a pulse-amplitude indication (i.e., aseries of detected pulse amplitudes and a series of smoothened pulseamplitudes) and a measurement-condition indication both of which areoutput by an output device of the apparatus of FIG. 50;

FIG. 54 is a view corresponding to FIG. 53, showing another example of aseries of detected pulse amplitudes and a series of smoothened pulseamplitudes output by the apparatus of FIG. 50;

FIG. 55 is a view corresponding to FIG. 53, showing yet another exampleof a series of detected pulse amplitudes and a series of smoothenedpulse amplitudes output by the apparatus of FIG. 50;

FIG. 56 is a view corresponding to FIG. 53, showing yet another exampleof a series of detected pulse amplitudes and a series of smoothenedpulse amplitudes output by the apparatus of FIG. 50;

FIG. 57 is a view corresponding to FIG. 53, showing yet another exampleof a series of detected pulse amplitudes and a series of smoothenedpulse amplitudes output by the apparatus of FIG. 50;

FIG. 58 is a view of another example of a measurement-conditionindication output by the apparatus of FIG. 50; and

FIG. 59 is a flow chart including steps carried out to select and outputan evaluation message corresponding to a determined correction degree C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIG. 1, there is shown an automatic blood pressure(BP) measuring apparatus 8 embodying the present invention. In thefigure, reference numeral 10 designates a housing of the BP apparatus 8.The BP apparatus 8 includes a tunnel-like, cylindrical hollow sectionwhich serves as an arm receiver 14 into which a living subject such as apatient inserts his or her arm 12 for measurement of his or her bloodpressure value. Inside the arm receiver 14, an elongate belt 18 issupported such that the belt 18 takes a generally cylindrical shape. Aninflatable cuff 16 constituted by a bag-like flexible cloth and a rubberbag enveloped in the flexible cloth, is secured to the inner surface ofthe elongate belt 18. The BP apparatus 8 has an operation panel 20including a START switch 22, a STOP switch 24, a printer 26, and a cardinsertion slot 28. The BP apparatus 8 also has a display panel 30including a SAP display 32, a DAP display 34, a PR display 36, and adate and time display 38. The abbreviations `SAP`, `DAP`, and `PR`represent a systolic and a diastolic blood pressure and a pulse rate,respectively. The BP apparatus 8 has a speaker 40 provided in the sidewall thereof. The speaker 40 issues various sound messages.

FIG. 2 shows the electric arrangement of the BP apparatus 8. As shown inthe figure, the inflatable cuff 16 is connected via piping 48 to apressure sensor 42, a cuff-pressure regulator valve 44, and an air pump46. The elongate belt 18, which takes a cylindrical shape in the armreceiver 14 and to which the inflatable cuff 16 is secured, is fixed atone of the longitudinal ends thereof to the housing 10 and is connectedat the other longitudinal end to a rotatable drum 52 which is driven orrotated by a direct-current (DC) motor 50 via reduction gears. Theelongate belt 18 or inflatable cuff 16 is tightened, and loosened, bythe DC motor 50.

The output signal of the pressure sensor 42 is fed to a band-pass filter54 which selectively transmits a heartbeat-synchronous oscillatorycomponent of the received pressure signal, as a pulse wave signal, SM,to an analog to digital (A/D) converter 58 of an arithmetic and controlcircuit 56. The pulse wave signal SM represents the pulse wave producedfrom the pressed arteries of the subject's arm 12 and propagated to theinflatable cuff 16 currently pressing the arm 12. The pressure signal ofthe pressure sensor 42 is also fed to a low-pass filter 60 whichselectively transmits a static component of the received signal, as acuff pressure signal, SK, to the A/D converter 58 of the control circuit56. The cuff pressure signal SK represents the change of static pressureof the inflatable cuff 16.

The arithmetic and control circuit 56 is essentially constituted by amicrocomputer including a central processing unit (CPU) 62, a read onlymemory (ROM) 64, a random access memory (RAM) 66, an input interfacecircuit 68, an output interface circuit 70, and data bus 61. The CPU 62processes input signals according to the control programs pre-stored inthe ROM 64 by utilizing the temporary-storage function of the RAM 66,and produces drive signals and display signals. For blood pressuremeasurement, the CPU 62 feeds drive signals to the DC motor 50 totightly wind the inflatable cuff 16 around the upper arm 12 of theliving subject being currently inserted in the arm receiver 14,subsequently to the air pump 46 to inflate the cuff 16 and thereby pressthe upper arm 12, and then to the cuff-pressure regulator valve 44 togradually reduce the cuff pressure of the cuff 16, so that the CPU 62receives during reduction of the cuff pressure the pulse wave signal SMand the cuff pressure signal SK from the pressure sensor 42 via therespective filters 54, 60, determines based on the received signals SM,SK the SAP and DAP blood pressure values of the subject in the knownoscillometric BP measuring process, feeds display signals to the SAP andDAP displays 32, 34 to indicate the determined SAP and DAP values,respectively, and stores the SAP and DAP values in a blood-pressure (BP)memory area 87 of a memory device 86. The cuff 16, air pump 46, pressuresensor 42, filters 54, 60, and control device 56 cooperate with eachother to provide a BP measuring device 100.

The BP memory area 87 of the memory device 86 is capable of storing anumber of sets of blood pressure data each of which represents a pair ofSAP and DAP values obtained in a corresponding one of a number of bloodpressure measurements of the living subject. The memory device 86 alsoincludes a waveform memory area 88. The CPU 62 stores, in the waveformmemory area 88, a waveform of the pulse wave signal SM obtained at aprescribed pressure, for example, a mean blood pressure (MAP) value ofthe subject or a certain pressure lower than the MAP value, in each ofthe blood pressure measurements of the subject. Furthermore, the memorydevice 86 includes an evaluated-value (EV) memory area 89. The CPU 62evaluates a characteristic of each of the waveforms of the pulse wavesignal SM stored in the waveform memory area 88, provides an evaluatedvalue of each waveform, and stores in the EV memory area 89 theevaluated value of the waveform in each of the blood pressuremeasurements of the subject. The memory device 86 may be a well knownmemory device such as a magnetic disk, magnetic tape, volatilesemiconductor memory, or non-volatile semiconductor memory.

In each of blood pressure measurements, the CPU 62 operates the printer26 to record, on a recording sheet 110 (FIG. 5), graphicalrepresentations 116 representing the BP values accumulatively stored inthe BP memory area 87 and the waveform evaluated values accumulativelystored in the EV memory area 89. In each blood pressure measurement, theCPU 62 controls the printer 26 to additionally print, on the recordingsheet 110, waveform representations 118 including curves 122representing the waveforms accumulatively stored in the waveform memoryarea 88, along a time axis 124 identical with a common time axis 120 ofthe graphs 116.

The BP memory area 87 of the memory device 86 stores a number of pairsof SAP and DAP values of the living subject that are measured using theinflatable cuff 16, air pump 46, pressure sensor 42, etc. The band-passfilter 54 provides the pulse wave signal SM representing the pulse waveproduced from the arteries of the arm 12 of the subject in synchronismwith the heartbeats of the subject while the cuff pressure of the cuff16 is gradually decreased in each blood pressure measurement. Thewaveform memory area 88 stores the waveform of the pulse wave signal SMprovided by the band-pass filter 54, in each blood pressure measurement.The printer 26 outputs the BP values accumulatively stored in the BPmemory area 87, in the order of measurement of those BP values, andoutputs the curves 122 representing the waveforms accumulatively storedin the waveform memory area 88, in the order of storage of thosewaveforms and in parallel to the BP values. Thus, the present BPapparatus 8 is very easy to use, and outputs the BP values and waveformsof the living subject in a side-by-side relation with each other.Medical workers can read the change of the waveforms in relation withthe change of the BP values, and can make a diagnosis on whether thesubject has a heart disease.

The ROM 64 stores a control program represented by a flow chart shown inFIG. 3. The flow chart includes Step S10 at which the CPU 62 processesor modifies the waveforms of the pulse wave signals SM stored in thewaveform memory area 88 of the memory device 86, so that the respectiveamplitudes of the modified waveforms are equal to one another and thethus modified waveforms are output on the recording sheet 110 by theprinter 26. Thus, medical workers can compare the waveforms with oneanother and recognize the time change of the waveforms.

The flow chart of FIG. 3 also includes Step S11 at which the CPU 62processes or modifies the waveforms of the pulse wave signals SM storedin the waveform memory area 88, so that the respective wavelengths ofthe modified waveforms are equal to one another and the thus modifiedwaveforms are output on the recording sheet 110 by the printer 26. Thus,medical workers can compare the waveforms with one another and recognizethe time change of the waveforms.

The flow chart of FIG. 3 further includes Step S8 at which the CPU 62evaluates a characteristic of each of the waveforms accumulativelystored in the waveform memory area 88, provides an evaluated value ofthe characteristic of each waveform and stores, in the EV memory area89, the evaluated value of each waveform. The printer 26 outputs therespective evaluated values of the waveforms that have accumulativelybeen stored in the EV memory area 89, in the order of storage of thewaveforms in the waveform memory area 88. Thus, medical workers canquantitatively understand the time change of the pulse wave signals SMand can easily recognize the time change of the respective waveforms ofthe pulse wave signals SM.

The printer 26 outputs the respective graphs 116 of (a) the BP valuesaccumulatively stored in the BP memory area 87 and (b) the waveformevaluated values accumulatively stored in the EV memory area 89, eachalong the common time axis 120. In addition, the printer 26 outputs thecurves 122 representing the waveforms accumulatively stored in thewaveform memory area 88, in parallel with the above two graphs, alongthe identical time axis 124. That is, the printer 26 outputs the BPvalues and the waveform evaluated values, together with thecorresponding waveform curves, along the common time axis. Thus, medicalworkers can easily recognize the time change of the waveforms of thepulse waves of the living subject.

The CPU 62 is connected to a card reader 74 which receives a magneticcard 76 being inserted in the card slot 28 by the living subject andread identification (ID) data recorded on the magnetic card 76. The IDdata recorded on the magnetic card 76 identifies the living subjectcarrying the magnetic card 76.

Hereinafter, there will be described the operation of the presentautomatic BP measuring apparatus 8 constructed as described above, byreference to the flow chart of FIG. 3.

First, at Step S1, the CPU 62 judges whether a magnetic card 76 has beeninserted in the card reader 74 through the card slot 28. If a negativejudgment is made at Step S1, the current control cycle of this routineis ended. On the other hand, if a positive judgment is made, i.e., if amagnetic card 76 has been inserted, the control of the CPU 62 proceedswith Step S2 to read the ID data magnetically recorded on the magneticcard 76. The magnetic card 76 may be a product according to JapaneseIndustrial Standard, X6301 or X6302.

Step S2 is followed by Step S3 to judge whether the ID data read fromthe magnetic card 76 has been registered in the BP apparatus 8, i.e., isidentical with any of the sets of ID data stored in an ID data memoryarea (not shown) of the memory device 86. If a negative judgment is madeat Step S3, the control goes to Step S12 at which the CPU 62 controlsthe printer 26 to output, on a recording sheet 110, a message indicatingthat the ID data recorded on the magnetic card 76 has not beenregistered on the BP apparatus 8 and that you are requested to registeryour magnetic card 76 on the BP apparatus 8. In addition, the CPU 62controls the card reader 74 to eject the non-registered card 76.

On the other hand, if a positive judgment is made at Step 53, thecontrol of the CPU 62 goes to Step S4 to judge whether the START switch22 has been operated to start a blood pressure (BP) measurement. The CPU62 repeats Step S4 until a positive judgment is made. If a positivejudgment is made at Step S4, the control goes to Step S5, i.e., BPmeasure subroutine in which a systolic (SAP), a diastolic (DAP), and amean blood pressure (MAP), and a pulse rate (PR) value, of the livingsubject are measured or determined. In the BP measure subroutine, theCPU 62 operates, according to a pre-stored algorithm, for automaticallyincreasing the cuff pressure of the inflatable cuff 16 and determiningduring the reduction of the cuff pressure the SAP, DAP, and MAP valuesof the living subject in the known oscillometric BP measuring method.Specifically, the SAP and DAP values are determined based on the changeof respective amplitudes of pulses of the pulse wave signal SM obtainedduring the reduction of the cuff pressure. The MAP value is determinedas being equal to a cuff pressure at the time of occurrence of a pulsehaving a maximum amplitude. The PR value is determined based on a timedifference between two successive pulses of the pulse wave signal SM,i.e., pulse wave represented by the signal SM.

Step S5 is followed by Step S6 to store, in the BP memory area 87 of thememory device 86, data indicative of the SAP, DAP, MAP and PR valuesdetermined at Step S5, together with data indicative of the date andtime of measurement of those values, in relation with the ID dataidentifying the magnetic card 76 being currently inserted in the cardreader 74 and thereby identifying the living subject carrying the card76. Additionally, the CPU 62 commands the SAP, DAP, and PR displays 32,34, 36 to display the determined SAP, DAP, and PR values, respectively.

At the following Step S7, the CPU 62 stores, in the waveform memory area88, the waveform of one of the pulses of the pulse wave signal SM whichone pulse has been detected at a prescribed cuff pressure, or in aprescribed range of the cuff pressure, during the reduction of the cuffpressure. The waveform of one pulse is stored together with dataindicative of the date of detection of the pulse wave signal SM, both inrelation with the ID data identifying the living subject carrying the IDcard 76. The prescribed cuff pressure at which the waveform is detectedor obtained may be selected at around the MAP value of the subject, orat a pressure lower than the MAP value, or at the lowest possiblepressure in a pressure range between the MAP and DAP values of thesubject. For example, the CPU 62 selects, from all the pulses obtainedbetween the MAP and DIA values, one pulse obtained at the lowestpressure of all the pressures at which the respective pulses areobtained. The CPU 62 stores the waveform of the thus selected one pulsein the waveform memory 86. To this end, the CPU 62 utilizes the pulsewave signal SM supplied from the band-pass filter 54.

Step S7 is followed by Step S8 to evaluate a characteristic of thewaveform of one pulse SM stored in the waveform memory area 88, andprovide an evaluated value of the waveform characteristic of one pulseSM. The evaluate value may be one or both of (a) a slope value, SLOPE,related to an increasing portion of one pulse starting from a lower peakto a following upper peak of the signal SM, and (b) an MAP percentagevalue, % MAP, related to a decreasing portion of one pulse starting froman upper peak to a following lower peak of the signal SM. The valueSLOPE is defined as the greatest slope, (dP/dt)_(max), of the increasingportion of one pulse SM. The value % MAP is defined as the percentage(=100×a/b) of the MAP value (i.e., height, a, of the MAP value shown inFIG. 4) with respect to the amplitude, b, of one pulse SM (b is thepressure difference between the SAP and DAP values). The value SLOPEreflects the strength of the heart muscle of the living subject, andrelates to the amount of output of the heart of the subject. The value %MAP relates to the diastolic period of the heart of the subject, i.e.,resistance of the peripheral arterial vessels of the subject.

At the following Step S9, the CPU 62 stores, in the EV memory area 89,the waveform characteristic evaluated values determined at Step S8,i.e., the two values SLOPE, % MAP, with the date of detection of thepulse wave signal SM, in relation with the ID data identifying theliving subject. Step S9 is followed by Step S10 to modify the one-pulsewaveform stored in the waveform memory area 88 so that the modifiedwaveform takes a prescribed amplitude, i.e., prescribed differencebetween the upper and lower peaks of the waveform. Since amplitudes ofwaveforms easily change depending upon the cuff pressures at which thewaveforms are obtained through the cuff 16, the amplitude modificationof the waveforms at Step S10 ensures that the waveforms are clearlyoutput in parallel with one another on the recording sheet 110 and thatmedical workers easily compare those waveforms with one another.

At the following Step S11, the CPU 62 modifies the one-pulse waveformwhose amplitude has been modified at Step S10, so that the modifiedwaveform takes a prescribed wavelength, i.e., prescribed time lengthbetween the two successive lower peaks of the waveform. Sincewavelengths of waveforms easily change depending upon the pulse rates atwhich the waveforms are obtained through the cuff 16, the wavelengthmodification of the waveforms at Step S11 ensures that the waveforms areclearly output in parallel with one another on the recording sheet 110and that medical workers easily compare those waveforms with oneanother.

Step S11 is followed by Step S12 to control the printer 26 to output orrecord, on the recording sheet 110 shown in FIG. 5, the BP and PR datawhich have accumulatively been stored in the memory device 86 inrelation with the ID data read from the magnetic card 76. Specifically,in a left-hand and upper portion of the sheet 110, the printer 26records a name 112 of the living subject identified by the ID data.Beneath the name 112, the printer 26 records (a) a data list 114including the dates and times of measurement and the measured SAP, DAP,and RP values; (b) graphic representations 116 of various parameters;and (c) waveform representations 118. The graphic representations 116include (b1) a series of bars the upper and lower ends of each of whichrepresent an SAP and a DAP blood pressure value, (b2) a series ofsymbols, Δ, each of which represents a PR value, (b3) a series ofsymbols, O, each of which represents a value SLOPE, and (b4) a series ofsymbols, ·, each of which represents a value % MAP, all in relation withcorresponding times of measurement, along the common axis of abscissae,i.e., first time axis 120. The waveform representations 118 include aseries of curves 122 representing the waveforms accumulatively stored inthe waveform memory area 88, each in relation with the time ofmeasurement of corresponding BP values, along the first time axis 120and the second time axis 124 identical with the first time axis 120.

As is apparent from the foregoing description of the first embodiment,the band-pass filter 54 of the BP apparatus 8 provides a pulse wavesignal SM representing a pulse wave produced from arteries of a livingsubject in synchronism with the heartbeats of the subject while eachblood pressure measurement is carried out on the subject at Step S5 ofFIG. 3. The waveform of one pulse of the pulse wave signal SM providedby the band-pass filter 54 is accumulatively stored in the waveformmemory area 88 at Step S7. At Step S12, the printer 26 outputs (a) theBP values accumulatively stored in the BP memory area 87, in the orderof measurement, on the recording sheet 110, and (b) the curves 122representing the waveforms accumulatively stored in the waveform memoryarea 88, in the order of storage, in parallel with the BP values, bothalong the common time axis 120. The BP measuring apparatus 8 is veryeasy to operate and simultaneously outputs the BP values and waveformsof a living subject in parallel with each other. Medical workers caneasily recognize a time change of the waveforms in relation with a timechange of the BP values, and can make a diagnosis on whether the subjecthas a heart disease or not.

In the first embodiment, the band-pass filter 54 is primarily employedfor extracting, as a pulse wave signal SM, a pressure oscillationproduced in the cuff 16 in synchronism with the heartbeats of a livingsubject in a blood pressure measurement, and the CPU 62 is programmed toutilize the waveform of the pulse wave signal SM provided by theband-pass filter 54. Thus, the BP apparatus 8 does not require anexclusive sensor for detecting a pulse wave from the subject, and enjoysa simpler construction and a lower manufacturing cost.

In the first embodiment, the CPU 62 modifies, at Step S10 of FIG. 3,each waveform stored in the waveform memory area 88, in such a way thateach modified waveform has a prescribed amplitude, and the printer 26outputs at Step S12 the modified waveforms each having the prescribedamplitude. Thus, medical workers can easily compare the output waveformswith one another and recognize a time change of the waveforms.

Also, in the first embodiment, the CPU 62 modifies, at Step S11, eachwaveform stored in the waveform memory area 88, in such a way that eachmodified waveform has a prescribed wavelength, and the printer 26outputs at Step S12 the thus modified waveforms each having theprescribed wavelength. Thus, medical workers can easily compare theoutput waveforms with one another and recognize a time change of thewaveforms.

Moreover, in the first embodiment, the CPU 62 evaluates, at Step S8, acharacteristic of each waveform stored in the waveform memory area 88,provides an evaluated value of each waveform, and stores the waveformevaluated value in the EV memory area 89. At Step S12, the printer 26outputs the waveform evaluated values accumulatively stored in the EVmemory area 89, in the order of evaluation, i.e., in the order ofdetection of waveform. Thus, medical workers can recognize aquantitative change of the waveforms and more easily recognize a timechange of the waveforms.

Furthermore, in the first embodiment, the printer 26 outputs, in thegraphs 116, the BP values accumulatively stored in the BP memory area87, and the waveform evaluated values accumulatively stored in the EVmemory area 89, along the common first time axis 120. Simultaneously,the printer 26 outputs the curves 122 corresponding to the waveformsaccumulatively stored in the waveform memory area 88, in parallel withthe graphs 116, along the first or second time axis 120, 124. Thus,medical workers can still more easily recognize a time change of thewaveforms.

The BP apparatus 8 or the printer 26 may be modified to record, at StepS12, measurement data 112, 114, 126, 128 on a recording sheet 125 asshown in FIG. 6. The recording sheet 125 has a width greater than thatof the recording sheet 110 shown in FIG. 5. Alternatively, the BPapparatus 8 may further include a display device, such as a cathode raytube (CRT), for displaying the same visual representation as thatrecorded on the recording sheet 125 of FIG. 6. In a left-hand and upperportion of the recording sheet 125, the printer 26 records a name 112 ofa living subject identified by the ID data read from a magnetic card 76.The printer 26 records, beneath the name 112, a data list 114 includingdates and times of measurement and measured SAP, DAP, and RP values;and, on the right-hand side of the data list 114, graphicrepresentations 126 of various parameters, and waveform representations128. The graphic representations 126 show a series of bars the right andleft ends of each of which represent an SAP and a DAP value (mmHg), aseries of symbols, ∇, each of which represents a PR value, a series ofsymbols, O, each of which represents a value SLOPE, and a series ofsymbols, , each of which represents a value % MAP, all in relation withcorresponding times of measurement, along a common axis of ordinates,i.e., time axis 130. The waveform representations 128 include a seriesof curves 132 representing the waveforms accumulatively stored in thewaveform memory area 88, each in relation with the time of measurementof corresponding BP values, along the time axis 130. The time axis 130need not be explicitly indicated on the recording sheet 125, but may beprovided implicitly, without any indication thereof, on the sheet 125.Between the waveforms 128 and the graphs 126, the recording sheet 125shows a series of values % MAP and a series of values SLOPE. Theleft-hand value "13" of, e.g., a measurement result "13-5" of the SLOPEsrepresents a maximum slope of the increasing portion of one pulse,whereas the right-hand value "5" represents a maximum slope of thedecreasing portion of the same pulse.

Otherwise, the BP apparatus 8 or the printer 26 may be modified torecord, at Step S12, measurement data 112, 134, 136, 138 on a recordingsheet 135 as shown in FIG. 7. In a left-hand and upper portion of therecording sheet 135, the printer 26 records a name 112 of a livingsubject identified by the ID data read from a magnetic card 76. Theprinter 26 records, beneath the name 112, a data list 134 includingdates and times of measurements and measured SAP, DAP, and RP values;and, on the right-hand side of the data list 134, graphicrepresentations 136 of various parameters, waveform representations 138,and names 146 of administered medicines. The graphic representations 136show a series of bars the right and left ends of each of which representa SAP and a DAP blood pressure value (mmHg), and a series of symbols, O,each of which represents a PR value, all in relation with correspondingtimes of measurements, along a common axis of ordinates, i.e., time axis140. The waveform representations 138 include, in a ruled area 148, aseries of curves 142 representing the waveforms accumulatively stored inthe waveform memory area 88, each in relation with the time ofmeasurement of corresponding SAP and DAP values, along a time axis 144as one side of the ruled area 148 and additionally along the time axis140. The names of administered medicines 146 indicate the medicinesadministered to the living subject when blood pressure measurements arecarried out on the subject. Data representing the medicine names 146 maybe input to the BP apparatus 8 through operation of a keyboard (notshown) connected to the apparatus 8, or may be transmitted from a hostcomputer (not shown) which processes medical information on the livingsubject. The medicine data may be input or transmitted to the controlcircuit 56 of the BP apparatus 8 before Step S4 of FIG. 3.

Since the medicine names 146 are indicated together with the graphs 136and waveforms 138, medical workers can recognize the time changes ofmedical effects of the medicines administered to the subject to treatthe subject's heart disease. The rules 148 are provided for enabling themedical workers to more easily read the time change of the waveforms142. However, the rules 148 may be omitted. In the data list 134, thesize of the figures representing the PR values are smaller than that ofthe figures representing the BP values, for preventing any confusion ofthe BP and PR values. However, the BP and RP values may be recorded inthe same size.

It is to be understood that in the first embodiment the BP apparatus 8may be modified in various manners.

In the first embodiment relating to the BP apparatus 8, it is possibleto omit all steps, or one or more specific steps, out of Steps S8through S11 of the flow chart of FIG. 3.

In the flow chart of FIG. 3, it is possible to carry out Steps S10 andS11 before Step S7. In this case, at Step S7, the CPU 62 stores, in thewaveform memory area 88, the waveforms which had been modified withrespect to the amplitudes and wavelengths thereof at Steps S10 and S11.

At Step S5 of FIG. 3, the CPU 62 determines BP values according to theknown oscillometric method. However, the BP apparatus 8 may be modifiedto measure BP values of a living subject according to the knownKorotkoff-sound method where one or more BP values are determined basedon detected Korotkoff sounds. In this case, the BP apparatus 8 isprovided with a microphone which detects Korotkoff sounds produced fromarteries of a body portion (e.g., upper arm) of a living subject whilethe cuff pressure pressing the upper arm is changed, i.e., graduallydecreased or increased.

The automatic BP measuring apparatus 8 starts measuring BP values of aliving subject if ID data recorded on a magnetic card 76 being insertedtherein by the subject is found to be identical with ID data alreadyregistered in the apparatus 8. However, the principle of the presentinvention is applicable to other types of BP measuring apparatus, forexample, apparatus which continuously repeats BP measurements of aliving subject at regular intervals of time (e.g., at a prescribedinterval of 5 to 30 minutes) by using an inflatable cuff being woundaround a body portion of the subject. In this case, the apparatus mayhave a display device (e.g., CRT) which displays the repetitivelymeasured BP values, and the waveforms obtained therewith, along a commontime axis.

Next, there will be described a second embodiment of the presentinvention. The second embodiment relates a blood pressure (BP) measuringapparatus 208 having an electric arrangement shown in FIG. 8. The BPmeasuring apparatus 208 is similar to the BP measuring apparatus 8 shownin FIGS. 1 and 2. Therefore, the same reference numerals as used inFIGS. 1 and 2 are used to designate corresponding elements or parts ofthe BP apparatus 208, and the description of those elements or parts isomitted. The following description will be focused on the differences ofthe BP apparatus 208 from the BP apparatus 8.

In the blood pressure and pulse rate (PR) measuring process, the BPapparatus 208 operates similar to the BP apparatus 8. Specifically, aCPU 62 of an arithmetic and control device 56 feeds drive signals to aDC motor 50, subsequently to an air pump 46, and then to a cuff-pressureregulator valve 44, so that the CPU 62 receives a pulse wave signal SMand a cuff pressure signal SK from a pressure sensor 42 via respectivefilters 54, 60, determines based on the received signals SM, SK the BPand PR values of a living subject 12 such as a patient according toknown algorithms pre-stored in the ROM 64, feeds display signals to anSAP, a DAP, and a PR display 32, 34, 36 to display the measured BP andPR values, and generates print signals to a printer 26 to record themeasured values on recording sheets 292a, 292b, and 292c respectivelyshown in FIGS. 10, 11, and 12.

In the present embodiment, the CPU 62 accumulatively stores the measuredBP and PR values of the subject 12, in a physical-information (PI)memory area 284 of a memory device 280 connected to the control device56. The memory device 280 may be constituted by a magnetic disk, amagnetic tape, or a semiconductor memory.

The control device 56 or CPU 62 is connected to a speaker drive circuit277 which supplies drive signals to a speaker 40 to generate sounds orvoices such as messages to the subject 12 or medical workers. The CPU 62is also connected to a known image reader 278 which reads images from anoriginal bearing an original image.

The memory device 280 includes an evaluation-comment (EC) memory area282 in which are pre-stored a plurality of sets of evaluation-commentdata each of which is indicative of a corresponding one of a pluralityof predetermined BP evaluation comments relating to the blood pressureof the subject 12, or the time change of the BP values accumulativelystored in the PI memory area 284. The CPU 62 selects, according to thecontrol programs pre-stored in the ROM 64, one of the stored evaluationcomments which corresponds to the BP values of the subject 12 measuredby a BP measuring device 100 in a current operation cycle, and/or thecollected BP values of the subject 12 measured by the BP device 100 andaccumulatively stored in the PI memory area 284. The collected BP valuesof the subject 12 contain the BP values obtained by the BP device 100 inthe current operation cycle and the BP values obtained by the BP device100 in the prior operation cycles. The CPU 62 supplies sound signals tothe speaker drive circuit 278 to drive the speaker 40 and thereby issuethe selected one evaluation comment.

The memory device 280 further includes an output-image (OI) memory area286 in which are pre-stored a plurality of sets of evaluation-image dataeach of which is representative of a corresponding one of a plurality ofpredetermined BP evaluation pictorial images relating to the bloodpressure of the subject 12, or the time change of the BP valuesaccumulatively stored in the PI memory area 284. The CPU 62 selects,according to the control programs pre-stored in the ROM 64, one of thestored evaluation images which corresponds to the BP values of thesubject 12 measured by a BP measuring device 100 in a current operationcycle, and/or the collected BP values of the subject 12 measured by theBP device 100 and accumulatively stored in the PI memory area 284. TheCPU 62 supplies print signals to the printer 26 to record the selectedone evaluation image on the recording sheet 292a, 292b, 292c.

The memory device 280 additionally includes an identification (ID) datamemory area 288 which stores one or more sets of ID data each of whichidentifies a corresponding one of a plurality of living subjects such aspatients. The living subjects are registered in the BP apparatus 208 bystoring their ID data in the ID memory area 288. The memory device 280has a subject-name (SN) memory area (not shown) which stores a pluralityof sets of subject-name data each of which is representative of the nameof a corresponding one of the subjects. When a set of ID data is storedin the ID memory area 288, a set of subject-name data is stored in theSN memory area. If the ID data read from a magnetic card 76 beinginserted in a card reader 74 are found to be identical with one of thesets of ID data stored or registered in the ID memory area 288, the CPU62 controls the printer 26 to record, on the recording sheet 292a, 292b,292c, the name of a living subject corresponding to the read ID data,together with the measured BP values obtained in the current operationcycle and a graphic representation showing the time change of the BPvalues accumulatively stored in the PI memory area 284.

The memory device 280 includes a medicine-related comment (MC) memoryarea 290 in which are pre-stored a plurality of sets of medicine-relatedcomment data each of which is indicative of a corresponding one of aplurality of predetermined medicine-related comments relating to aplurality of medicines which may be administered by doctors to theliving subject 12. The BP apparatus 208 has a plurality of operable keys272 respectively corresponding to the plurality of medicines. When oneof the operable keys 272 is pushed by a doctor, the CPU 62 selects oneof the medicine-related comments stored in the MC memory area 290 andcontrols the printer 26 to record the selected one medicine-relatedcomment, together with the BP values and BP graph, on the recordingsheet 292a, 292b, 292c.

The BP apparatus 208 has an image/comment edit device 273 which isoperable for inputting a command to the CPU 62 so that the CPU 62controls the image reader 278 to read an original image and/or anoriginal comment recorded on an original sheet. The image reader 278includes a display (not shown) for displaying the read original imageand/or comment. The edit device 273 is operable for editing the originalimage and/or comment being displayed on the display. The edit device 273may include a cursor movable on the display, and a mouse or keyboardoperable for moving the cursor on the display. The edit device 273 iscapable of enlarging, reducing, moving, and partly cutting out theoriginal image and/or comment on the display. The CPU 62 stores theimage and/or comment edited by the edit device 273, in the OI memoryarea 286 and/or the MC memory area 290, respectively.

The BP apparatus 208 includes a random signal generator circuit 294which generates a plurality of different random signals. The OI memoryarea 286 is also capable of storing a plurality of random selectableimages which do not relate to the blood pressure of the subject 12 andwhich correspond to the random signals produced by the generator circuit294. If a blood pressure measurement of the subject 12 is carried outwith the BP apparatus 208 being placed in a random image select mode asone of selectable operation modes, as a result of operation of a modeselect dial (not shown) provided on an operator panel 20, the CPU 62selects one of the random selectable images which corresponds to arandom signal being currently produced by the circuit 294, and recordsthe thus random selected one image together with the BP values and BPgraph, on the recording sheet 292a, 292b, 292c.

The BP apparatus 208 further includes a clock circuit 296 which providesa time signal indicative of a current date and time. The OI memory area286 is also capable of storing a plurality of time-related selectableimages which do not relate to the blood pressure of the subject andwhich are related to the time signals produced from the clock circuit296. If a blood pressure measurement of the subject 12 is effected withthe BP apparatus 208 being placed in a time-related image select modeestablished by operating the mode select dial, the CPU 62 selects one ofthe time-related selectable images which corresponds to a current dateand time provided by the clock circuit 296, and records the thusselected one time-related image together with the BP values and BPgraph, on the recording sheet 292a, 292b, 292c.

In the second embodiment, the BP values measured by the BP measuringdevice 100 are stored in the PI memory area 284 of the memory device 280each time a blood pressure measurement is carried out on the subject 12.The OI memory area 286 stores different evaluation images relating tothe blood pressure of the subject 12; a plurality of different groups ofevaluation images (described later); different images relating to thedates and times of measurements provided by the clock circuit 296; anddifferent images corresponding to random signals or values provided bythe random signal generator circuit 294. The CPU 62 selects, from the OImemory area 286, one of the evaluation images which corresponds to thecurrent BP values of the subject 12 measured by the BP measuring device100. The EC memory area 282 stores different evaluation messages usedfor evaluating the BP values measured by the device 100. The CPU 62selects, from the EC memory area 282, one of the evaluation commentswhich corresponds to the current BP values measured by the device 100.The printer 26 records, on the recording sheet 292a, 292b, 292c, theselected evaluation image and the selected evaluation comment togetherwith a list of the BP values obtained by the device 100 in several BPmeasuring operations and with a BP graph representing the time change ofthose BP values.

The CPU 62 can select, from the OI memory area 286, one of the differentgroups of evaluation images which is specified by the ID data read fromthe magnetic card 76 being inserted in the card reader 74. The CPU 62can further select one of the selected group of evaluation images whichcorresponds to the current BP values of the subject 12, and control theprinter 26 to record the thus selected evaluation image together withthe list of BP values and the BP graph on the recording sheet 292a,292b, 292c.

The medicine select keys 272 are selectively operable by doctors forspecifying and inputting one of different blood-pressure controlmedicines which may be administered to patients. The MC memory area 290stores different comments related to the different blood-pressurecontrol medicines. While a medicine-related comment output mode isselected on the BP apparatus 208, the CPU 62 selects, from the MC memoryarea 290, one of the medicine-related comments which corresponds to themedicine input by a doctor through operation of one of the select keys272, and controls the printer 26 to record the selected medicine-relatedcomment together with the BP values measured by the BP measuring device100 on the recording sheet 292a, 292b, 292c.

With a random image output mode being selected on the BP apparatus 208,the CPU 62 selects, from the OI memory area 286, one of the randomselectable images which corresponds to the random signal or valueprovided by the random signal generator circuit 294, and controls theprinter 26 to record the thus random selected image together with the BPvalues and the BP graph on the recording sheet 292a, 292b, 292c.

Similarly, with a time-related image output mode being selected on theBP apparatus 208, the CPU 62 selects, from the OI memory area 286, oneof the time-related selectable images which corresponds to the timesignal, i.e., current date and time, provided by the clock circuit 296,and operates the printer 26 to record the selected one time-relatedimage together with the BP values and the BP graph on the recordingsheet 292a, 292b, 292c.

Furthermore, with an image edit mode being selected, the CPU 62controls, in response to operation of the image edit device 273, theimage reader 278 to read in an original image from an original anddisplay the read-in original image on the display of the reader 278.Medical workers can edit the original image on the image reader 278, byenlarging, reducing, and moving the image and cutting out a part orparts of the image. Similarly, the medical workers can edit an originalcomment that may be input to the image reader 278 independently of anoriginal image. The CPU 62 stores the thus edited image and/or commentin the OI memory area 286 and/or the MC memory area 290, respectively.

There will be described the operation of the BP measuring apparatus 208.

FIG. 9 shows a flow chart representing a control program according towhich the BP apparatus 208 carries out a BP evaluation mode in which theapparatus 208 outputs the measured, current BP values of a livingsubject and an evaluation image and an evaluation comment which evaluatethe current BP values of the subject 12.

First, at Step SS1, the CPU 62 judges whether the operation of the BPapparatus 208 has been started, by identifying whether a magnetic card76 has been inserted in a card insertion slot 28 of the card reader 74,or a main switch (not shown) has been operated. If a negative judgmentis made at Step SS1, Step SS1 is repeated. On the other hand, if apositive judgment is made, the control of the CPU 62 proceeds with StepSS2 to control the card reader 74 to read the ID data recorded on the IDcard 76 being inserted in the card slot 28. The CPU 62 temporarilystores, in the RAM 66, the ID data read by the card reader 74.

Step SS2 is followed by Step SS3 to judge whether the set of ID dataread from the card 76 is identical with one of the sets ID data storedor registered in the ID memory area 288. If a negative judgment is madeat Step SS3, the control of the CPU 62 goes to Step SS4 where the set ofID data is stored or registered in the ID memory area 288 according toan ID data register routine. Step SS4 is followed by Step SS5. On theother hand, if a positive judgment is made, the control of the CPU 62directly proceeds with Step SS5 to judge whether a START switch 22 hasbeen operated to start a BP measurement.

The CPU 62 repeats Step SS5 until a positive judgment is made at thisstep. If a positive judgment is made at Step SS5, the control goes toStep SS6, i.e., BP measure subroutine in which a systolic (SAP), adiastolic (DAP), a mean blood pressure (MAP) value, and a pulse rate(PR) value, of the living subject 12 are measured or determined. In theBP measure subroutine, the CPU 62 operates, according to a pre-storedalgorithm, for automatically raising the cuff pressure of an inflatablecuff 16 and determining during the reduction of the cuff pressure theSAP, DAP, and MAP values of the living subject 12 in to the knownoscillometric BP measuring method. For example, the SAP value may bedetermined as being equal to a cuff pressure at the time of occurrenceof a first maximum difference out of the differences obtained bysuccessively calculating the difference of respective amplitudes of eachpair of successive pulses of the pulse wave signal SM supplied duringthe reduction of the cuff pressure. Similarly, the DAP value may bedetermined as being equal to a cuff pressure at the time of occurrenceof a second maximum difference out of those differences. The MAP valueis determined as being equal to a cuff pressure at the time ofoccurrence of a pulse having a maximum amplitude out of the pulses. ThePR value is determined based on a time difference between two successivepulses of the pulse wave signal SM.

Step SS6 is followed by Step SS7 to store, in the PI memory area 284,data indicative of the BP and PR values determined at Step SS6, togetherwith data indicative of the date and time provided by the clock circuit296, in relation with the ID data obtained at Step SS2. Additionally,the CPU 62 commands the SAP, DAP, and PR displays 32, 34, 36 to displaythe measured SAP, DAP, and PR values, respectively.

At the following Step SS8, the CPU 62 selects, from the OI memory area286, one of the evaluation images which corresponds to the current BPvalues measured at Step SS6 and selects, from the EC memory area 282,one of the evaluation comments which corresponds to the current BPvalues measured at Step SS6.

Step SS8 is followed by Step SS9 where the CPU 62 controls the printer26 to record or print, on the recording sheet 292 (292a, 292b, 292c)shown in FIGS. 10, 11, or 12, (a) a name 232 of the subject 12corresponding to the ID data read from the card 76; (b) a date and timewhen the current BP measurement is carried out; (c) current BP values236 (236a, 236b, 236c) measured at Step SS6; (d) a current PR value 238measured at Step SS6; (e) a list 240 of the BP values and PR valuesaccumulatively stored in the PI memory area 284; (f) a graphicrepresentation 242 (242a, 242b, 242c) of the BP values accumulativelystored in the PI memory area 284; (g) a graphic representation 244 ofthe PR values accumulatively stored in the PI memory area 284; (h) apictorial evaluation image 246 (246a, 246b, 246c) corresponding to thecurrent BP values; and (i) an evaluation comment 248 (248a, 248b, 248c)corresponding to the current BP values. FIG. 10 shows an example of anoutput by the BP apparatus 208 for normal BP values; FIG. 11 shows anexample of an output for somewhat abnormal BP values; and FIG. 12 showsan example of an output for abnormal BP values. The evaluation image andcomment 146a, 148a indicate that the current BP values are normal; theimage and comment 246b, 248b indicate that the current BP values aresomewhat abnormal; and the image and comment 246c, 248c indicate thatthe current BP values are abnormal.

It emerges from the foregoing description that in the second embodimentthe CPU 62 selects, from the output image (OI) memory area 286, one ofthe different evaluation images 246a, 246b, 246c which corresponds tothe current BP values of the living subject 12 measured by the BPmeasuring device 100 and controls the printer 26 to record, on therecording sheet 292a, 292b, 292c the selected evaluation image 246a,246b, 246c together with the list 240 of the BP values measured in theprior measuring operations and the BP graph 242 indicating the timechange of the prior and current BP values. Since the evaluation image246a, 246b, 246c corresponding to the current BP values is outputtogether with the BP values obtained in the past measuring operations,the living subject 12 or medical workers can visually identify anabnormality of the current BP values, and the subject 12 can rememberthe abnormal measurement result for a long time.

In addition, in the second embodiment, the printer 26 records, on therecording sheet 292a, 292b, or 292c shown in FIG. 10, 11, or 12, (a) thename 232 of the living subject 12; (b) the date and time of the currentmeasurement; (c) the current BP values 236a, 236b, 236c; (d) the currentPR value 238; (e) the list 240 of the prior BP and PR values; (f) thegraphic representation 242a, 242b, 242c of the prior and current BPvalues; (g) the graphic representation 244 of the prior and current PRvalues; (h) the evaluation image 246a, 246b, 246c corresponding to thecurrent BP values; and (i) the evaluation comment 248a, 248b, 248ccorresponding to the current BP values. Since medical workers or theliving subject 12 can carry the recording sheet 292a, 292b, 292c, the BPapparatus 208 eliminates the burden of writing down the BP and PR valuesdisplayed on the display panel 30 or keeping those values in mind.

Furthermore, in the second embodiment, since the BP graph 242a, 242b,242c representing the time change of the prior and current BP valuesobtained in the several BP measurements is output on the recording sheet292a, 292b, 292c, medical workers or the living subject 12 can easilyrecognize the history of the BP values of the subject 12.

While the BP apparatus 208 is placed in an evaluation-image change modeas a result of operation of the mode select dial (not shown), theapparatus 208 or CPU 62 operates according to a control programrepresented by the flow chart of FIG. 13 and obtained by adding StepSS71 between Steps SS7 and SS8 of the flow chart of FIG. 9. As describedpreviously, the output image (OI) memory area 286 stores a plurality ofgroups of evaluation images. Since a normal (or abnormal) BP rangechanges depending upon sex, age, patient's medical history, etc., it isnot appropriate to use a single group of evaluation images to all thehuman beings including male and female, young and old, health and sick,etc. Therefore, a plurality of different groups of evaluation images areemployed for male, female, and old, respectively. The ID data recordedon the magnetic card 72 include the data indicative of the sex, age,medical history, etc. of the living subject 12 carrying the card 72, andthe CPU 62 selects, at Step SS71, one of the different groups ofevaluation images which one group corresponds the ID data read from thecard 72 at Step SS2. At Step SS8, the CPU 62 selects one of the selectedgroup of evaluation images which one image corresponds to the current BPvalues of the subject 12 measured by the measuring device 100. In thismode, the BP apparatus 208 outputs an evaluation image more accuratelyevaluating the current BP values of the male or female, young or oldsubject 12. Each image belonging to the group of evaluation images for,e.g., the male may contain the figure of a male person only. It may bethe case with the group of images for the female or the old. In thosecases, if an evaluation image indicating an abnormal blood pressure isoutput on a recording sheet, the output image will give a clearer visualimpression to the subject 12.

While the BP apparatus 208 is placed in a medicine-related commentoutput mode in response to operation of the mode select dial, theapparatus 208 or CPU 62 operates according to a control programrepresented by the flow chart of FIG. 14 and obtained by adding StepSS91 after Step SS9 of the flow chart of FIG. 9. As describedpreviously, the medicine-related comment (MC) memory area 290 stores aplurality of medicine-related comments relating to the medicines whichmay be administered by doctors to patients. At Step SS91, the CPU 62selects, from the MC memory area 290, one of the medicine-relatedcomments which corresponds to the medicine selected by a medical workerby pushing a corresponding one of the medicine select keys 272, andcontrols the printer 26 to record, e.g., on the recording sheet 292cshown in FIG. 12, the selected medicine-related comment in addition tothe other items 232-248. For example, a medicine-related comment mayread as follows: THIS MEDICINE, NAMED "XXXX", IS FOR IMPROVING YOURBLOOD PRESSURE. TAKE "Y" TABLETS AFTER EVERY MEAL FOR "Z" DAYS. In thecase where a doctor makes a diagnosis based on the measured BP values ofthe living subject 12 and hands out a selected blood pressure treatingmedicine to the subject 12, the BP apparatus 208 outputs, in response todoctor's input of data indicating the selected medicine throughoperation of a corresponding key 272, a comment related to the selectedmedicine together with the BP values on the recording sheet 92. Themedicine-related comment may describe the manner of use of the medicine,the virtue of the medicine, directions for use of the medicine, etc.Since the medicine-related comment is recorded on the sheet 92, thedoctor need not write down the comment on a sheet of paper or thesubject 12 need not keep it in mind.

While the BP apparatus 208 is placed in the random image output mode, orthe time-related image output mode, in response to operation of the modeselect dial, the apparatus 208 or CPU 62 operates according to a controlprogram represented by the flow chart of FIG. 15 and obtained by addingStep SS82 in place of Step SS8 of the flow chart of FIG. 9. As describedpreviously, the OI memory area 286 stores a plurality of randomselectable images that are not be related to blood pressure, and aplurality of time-related selectable images that are not be related toblood pressure. In the random image output mode, at Step SS82, the CPU62 selects, from the OI memory area 286, one of the random selectableimages which corresponds to the random signal or value provided by therandom signal generator circuit 294 and controls, at Step SS9, theprinter 26 to record, on the recording sheet 292, the random selectedimage in place of the evaluation image and message 246, 248 and inaddition to the other items 232-244. In the time-related image outputmode, at Step SS82, the CPU 62 selects, from the OI memory area 286, oneof the time-related selectable images which corresponds to the date andtime provided by the clock circuit 294 and controls, at Step SS9, theprinter 26 to record, on the recording sheet 292, the selectedtime-related image in place of the evaluation image and message 246, 248and in addition to the other items 232-244. The random or time-relatedselectable images may include images representing season's flowers,season's landscapes, etc. Those selectable images effectively operatefor visually impressing the measured BP values on the subject 12.

While the BP apparatus 208 is placed in the image/comment input and editmode in response to operation of the mode select dial, the apparatus 208or CPU 62 operates according to a control program represented by theflow chart of FIG. 16. The routine of FIG. 16 is carried out forpreparing various images to be stored in the OI memory area 286 andevaluation comments to be stored in the evaluation comment (EC) memoryarea 282. First, at Step SB1, the CPU 62 judges whether an originalimage has been read in from an original upon operation of a reading-inkey of the edit device 273. If a negative judgment is made at Step SB1,Step SB1 is repeated. On the other hand, if a positive judgment is made,the control of the CPU 62 goes to Step SB2 to control the image reader278 to read in the original image from the original, e.g., sheet bearingthe original image. The original image may be an original evaluationcomment. Usually, an original evaluation comment is recorded on adifferent or separate sheet from a sheet on which an original pictorialimage is recorded. At the following Step SB3, the CPU 62 edits theoriginal image in response to command signals input through operation ofthe edit device 273. Specifically, the CPU 62 enlarges or reduces thesize of the original image, moves the image, or cuts out a part of theimage, on the display of the image reader 278, so that the thus editedimage is suitable for being output on the recording sheet 92. Step SB3is followed by Step SB4 to judge whether the editing operation has beenfinished, by identifying whether an edit end key of the edit device 273has been operated. If a negative judgment is made at Step SB4, thecontrol of the CPU 62 returns to Step SB1 and the following steps. Onthe other hand, if a positive judgment is made at Step SB4, the controlgoes to Step SB5 to store the edited pictorial image in the OI memoryarea 286, and store the edited evaluation comment in the EC memory area282, with or without relation with data specifying the attributes of theedited image or comment. The attributes of an edited image or commentmay comprise (a) correspondence to the normal or abnormal BP values, (b)correspondence to a specific group for the male, female, young, or old,and (c) correspondence to a specific time such as a season or a month.In this mode, the BP apparatus 208 enables medical workers or otherusers to easily input and edit, and then register, in the apparatus 208,their desirable pictorial images and/or evaluation comments to be outputwith measured BP values on a recording sheet 92.

It is to be understood that the BP apparatus 208 may otherwise bemodified.

For example, while the control circuit 56 or CPU 62 is capable ofcarrying out all the control programs represented by the flow charts ofFIGS. 9, 13, 14, 15, and 16, the CPU 62 may be modified to carry out oneor more (but not all) of those programs.

While the memory device 280 is incorporated in the BP apparatus 208, itis possible to provide the memory device 280 outside the BP apparatus208 and connect the memory device 280 to the BP apparatus 208.Otherwise, the memory device 280 may be provided in a host computer towhich the BP apparatus 208 is connected via a communication line such asa telephone line.

Next, there will be described a third embodiment of the presentinvention. The third embodiment relates a blood pressure (BP) measuringapparatus 310 having a side view and a front view shown in FIGS. 17 and18, respectively. The BP measuring apparatus 310 is similar to the BPmeasuring apparatus 8 shown in FIGS. 1 and 2. Therefore, the samereference numerals as used in FIGS. 1 and 2 are used to designatecorresponding elements or parts of the BP apparatus 310, and thedescription of those elements or parts is omitted. The followingdescription will be focused on the differences of the BP apparatus 310from the BP apparatus 8.

The BP apparatus 310 has an automatic cuff winding device 330, shown inFIG. 18, which automatically winds an inflatable cuff 16 (and anelongate belt 18) around an upper arm of a living subject 12 (FIG. 1).For carrying out a BP measurement using the BP apparatus 310, thesubject 12 is required to insert his or her arm into an arm receiver 14in the same manner as that used on the BP apparatus 8 of FIG. 1. Morespecifically, the subject 12 inserts his or her arm in the receiver 14such that the elbow of the arm comes out of a rear-side opening of thetunnel-like arm receiver 14. In the present embodiment, the cuff windingdevice 330 includes the arm receiver 14, cuff 16, belt 18, and otherelements (described later); the cuff 16 serves as an inflatable bag; andthe belt 18 serves as a bag support. The cuff 16 and the belt 18cooperate with each other to provide an arm belt for pressing thesubject's arm.

In FIG. 17, the BP apparatus 310 is placed on a table 338. A first and asecond microswitch 340, 342 are provided at a top and a bottom of afront-side opening of the tunnel-like arm receiver 14. Each of the twomicroswitches 340, 342 has a contact member 340a, 342a and is embeddedin an inner surface 343 of a housing 10 such that the contact member340a, 342a is exposed to an inner space of the arm receiver 14. When thesubject's arm 12 is inserted in the receiver 14 and appropriatelypositioned relative to the receiver 14, the respective contact members340a, 342a of the two microswitches 340, 342 do not contact the upperarm 12 so that each contact member 340a, 342a takes its original stateand each microswitch 340, 342 takes its OFF state. Each microswitch 340,342 supplies a detection or non-detection signal indicative of its ON orOFF state, to a control device 368 (FIG. 18). Thus, the microswitches340, 342 serve as a detector for identifying whether the longitudinalaxis line of the subject's upper arm 12 is aligned with the longitudinalaxis line of the cylindrical arm receiver 14.

At the rear opening of the arm receiver 14, there is provided an elbowrest 344 having a curved surface shown in FIG. 17. The elbow rest 344 isfixed to the housing 10 with a fixing member (not shown). A thirdmicroswitch 346 is embedded in the curved surface of the elbow rest 344such that a contact member 346a of the microswitch 346 is exposed in thecurved surface. When the elbow of the subject's arm 12 is placed on theelbow rest 344, the contact member 346a of the switch 346 contacts theelbow and is pushed. Consequently, the third switch 346 is changed fromits OFF state to its ON state and supplies the detection signalindicative of the ON state to the control device 368. Thus, the thirdmicroswitch 346 identifies whether a sufficient length of the subject'sarm 12 has been inserted into the arm receiver 14.

As shown in FIG. 18, the BP apparatus 310 has, near the front endthereof, a left and a right adjustable legs 348, 348 which extenddownward from a bottom wall 10a of the housing 12. The length ofextension of the legs 348 from the outer surface of the bottom wall 10ais adjustable in a manner described later. When the length of extensionof the legs 348 is adjusted, the angle of inclination of the housing 10,therefore also the arm receiver 14, is changed relative to the table338.

Each leg 348 fits in a first cylinder 352 fixed to the inner surface ofthe bottom wall 10a using a metal member 350, such that each leg 348 isadvanceable outward from the corresponding first cylinder 352. Theamount of advancement of the legs 348 from the first cylinders 352,i.e., length of extension of the legs 348 from the bottom wall 10a isadjusted by a cylinder drive device 354 provided in the housing 10. Asshown in FIG. 19, the cylinder drive device 354 includes a secondcylinder 358 having a working fluid in a fluid chamber 356; a piston 362movable in the second cylinder 358 in an axial direction of the cylinder358 and fixed to a rack 360; a motor 366 having a reduction gear unitand a rotation shaft which supports a pinion 364 engaged with the rack360.

The motor 366 with the reduction gear unit is driven or rotated inresponse to a command from the control device 368, so that anappropriate fraction of the working fluid is supplied via piping 370from the fluid chamber 356 of the second cylinder 358 to a fluid chamber372 of the first cylinder 352, or so that an appropriate fraction of theworking fluid is removed via the piping 370 from the fluid chamber 372of the first cylinder 352 into the fluid chamber 356 of the secondcylinder 358. Each leg 348 is fixed to a piston 374 provided in thecorresponding first cylinder 352. When the amount of working fluid inthe fluid chamber 372 is increased or decreased and therefore the piston374 is moved forward or backward in the first cylinder 352, the amountof advancement of each leg 348 from the corresponding first cylinder 352is adjusted. Since the two first cylinders 352, 352 are connected viathe piping 370 and a bypass passage 376 to the cylinder drive device354, the single drive device 354 operates for simultaneously adjustingthe advancement amounts of the two legs 348, 348.

The control device 368 starts to adjust the angle of inclination of thehousing 10 or arm receiver 14, in response to the detection ornon-detection signal supplied from the third microswitch 346. Thecontrol device 368 continues to adjust the inclination angle of thehousing 10 so long as at least one of the first and second microswitches340, 342 continues to supply the detection signal indicative of the ONstate to the control device 368, i.e., so long as the subject's arm 12continues to contact at least one of the top and bottom of the frontopening of the arm receiver 14. In the present embodiment, theadjustable legs 348, first cylinders 352, and cylinder drive device 354cooperate with each other to serve as an arm-receiver positioningdevice. The control device 368 may be constituted by a microcomputer.

When the BP apparatus 310 is used to carry out a BP measurement on thesubject 12, a START switch 22 is operated, and then the subject insertshis or her arm 12 into the arm receiver 14 from the front openingthereof and places the elbow of the arm 12 on the elbow rest 344. If asufficient length of the arm 12 is inserted into the receiver 14 and thethird microswitch 346 provided in the elbow rest 344 is placed in the ONstate, the control device 368 starts to adjust the inclination angle ofthe housing 10. If, in this situation, the first or second microswitch340, 342 is placed in the ON state as a result of contact of the contactmember 340a, 342a with the arm 12, the control device 368 controls themotor 366 to operate or rotate so that the working fluid is supplied to,or removed from, the fluid chambers 372 of the first cylinders 352.Thus, the amount of advancement of the legs 348 is adjusted. In the casewhere the first microswitch 340 is pushed by the arm 12, the motor 366is rotated in a counterclockwise direction as seen in FIG. 19, so thatthe legs 348 are advanced. On the other hand, in the case where thesecond microswitch 342 is pushed by the arm 12, the motor 366 is rotatedin a clockwise direction as seen in FIG. 19, so that the legs 348 areretracted. When the control device 368 does not receive any detectionsignal from the two microswitches 340, 342 as a result of the adjustingoperation, the control device 368 stops the operation of the cylinderdrive device 354 and starts to tight up the belt 18 and inflate the cuff16 by supplying a pressurized air to the cuff 16. Thus, a BP measurementis started. Since the tightening up of the belt 18 and the inflation ofthe cuff 16 wound around the subject's upper arm 12, and the BPmeasuring method using the cuff 16 are well known in the art, thedescription of those steps is omitted. Following completion of the BPmeasurement, the cuff 16 is deflated and the belt 18 is loosened,thereby permitting the subject to withdraw his or her arm 12 from thearm receiver 14. Thus, a series of steps are ended. Once a BPmeasurement has been started, the control device 368 does not operatethe cylinder drive device 354 again before the elbow of the arm 12 islifted up and the contact member 346a of the third microswitch 346 isrestored to the OFF state thereof. Since the motor 366 is provided withthe reduction gear unit, the amount of advancement of the legs 348cannot be changed with the motor 366 being stopped.

It emerges from the foregoing description of the the third embodimentthat when the arm 12 is inserted in the arm receiver 14 and the elbow ofthe arm 12 is placed on the elbow rest 344, the control device 368controls the cylinder drive device 354 to adjust the amount ofadvancement of the legs 348 so that each of the first and secondmicroswitches 340, 342 supplies a non-detection signal indicative of theOFF state in which the corresponding contact member 340a, 342a is notheld in contact with the arm 12. Stated differently, the control device368 controls the cylinder drive device 354 to adjust the angle ofinclination of the arm receiver 14 relative to the table 338 so that thelongitudinal axis line of the upper arm 12 is substantially aligned withthe longitudinal axis line (i.e., central axis line) of the arm receiver14. Thus, the present BP apparatus 310 establishes an appropriateposition of the arm receiver 14 relative to the subject's arm 12 wherethe arteries of the arm 12 are not locally or partially pressed by thecuff 16, without requiring the subject to adjust his or her arm 12relative to the receiver 14. Stated differently, the BP apparatus 310accurately measures the BP values of the subject 12 while permitting thesubject 12 to take a natural posture.

Since in the present embodiment the control device 368 starts to adjustthe inclination angle of the arm receiver 14 when the contact member346a of the third microswitch 346 is pushed under the elbow of thesubject's arm 12 and starts a BP measurement following completion of theadjusting of the inclination angle, the BP apparatus 310 carries out theBP measurement with the arm 12 being appropriately inserted in the armreceiver 14.

FIG. 20 shows another arm-receiver positioning device 377 which may beemployed, in place of the legs 348, cylinders 352, and drive device 354shown in FIG. 18, for adjusting the inclination angle of the housing 10of the BP apparatus 310 relative to the table 338. The positioningdevice 377 includes two legs 380, 380 each of which includes anexternally threaded axis portion 378; an internally threaded nut 382held in threaded engagement with the axis portion 378 of each leg 380and having teeth in an outer circumferential surface thereof; and amotor 388 having a rotation shaft 386 which supports a pinion 384 heldin engagement with the teeth of the nut 382. A fixing metal member 390having a hole (not shown) through which the axis portion 378 of each leg380 extends, holds the corresponding nut 382 such that the nut 382cannot be moved in an axial direction of the axis portion 378 of the leg380. Each adjustable leg 380 has an axial groove 392 formed in thethreaded outer surface of the axial portion 378. Since the metal member390 has a key (not shown) extending into the hole through which theaxial portion 378 extends, and held in engagement with the axial groove392 of the axial portion 378. Consequently, each leg 380 is preventedfrom being rotate about the axis thereof, and is permitted to displacein the axial direction thereof with rotation of the corresponding nut382. The motor 388 is fixed with a fixing metal member 394 to the innersurface of the bottom wall of the housing 10, and operates or rotates inresponse to a command from the control device 368. The two legs 388 areassociated with the corresponding motors 388, respectively. Thearm-receiver positioning device 377 may be made more compact than thepositioning device constituted by the legs 348, cylinders 352, and drivedevice 354 shown in FIG. 18. The motors 388 need not be provided with areduction gear unit unlike the motor 366 shown in FIG. 19.

FIGS. 21(A) and 21(B) show another detector 395 which may be employed,in place of the microswitches 340, 342 shown in FIG. 18, for identifyingwhether the longitudinal axis line of the upper arm 12 is substantiallyaligned with the longitudinal axis line of the arm receiver 14. Thedetector 395 includes a number of air chambers 396 provided on thebottom of the inner surface 343 of the tunnel-like arm receiver 14. Inthe present embodiment, the air chamber 396 includes twelve air chambers396a to 396l, i.e. first array of air chambers 396a to 396f and secondarray of air chambers 396g to 396l. Each array 396a-396f, 396g-396lextends parallel to the longitudinal axis line of the arm receiver 14.The air chambers 396h to 396l are not shown in FIG. 21(A) or 21(B) sincethose chambers are provided in rear of the air chambers 396b to 396fshown in FIG. 21(B). The twelve air chambers 396a-396l communicate withpressure switches 398a to 398l, respectively. When each air chamber 396is pressed, a pressure change is produced in the corresponding pressureswitch 398, which supplies a pressure signal indicative of the detectedpressure of each chamber 396, to the control device 368. When thesubject's arm 12 is inserted into the arm receiver 14 for a BPmeasurement, the control device 368 starts to adjust the inclinationangle of the housing 10, based on the pressure signals supplied from thepressure switches 398a-398l, so that the longitudinal axis line of theupper arm 12 is substantially aligned with the longitudinal axis line ofthe arm receiver 14. In the case where an angle, θ, of the longitudinalaxis line, A, of the upper arm 12 from the longitudinal axis line, O, ofthe arm receiver 14 is positive as shown in FIG. 21(b) (it is assumedthat any angle of rotation in a counterclockwise direction from thereference axis O is positive), the respective pressures in the airchambers 396e, 396f, 396k, 396l provided in the rear portion of the armreceiver 14 are increased. Accordingly, the control device 368 operatesfor increasing the inclination angle of the housing 10 and therebydecreasing the respective pressures of those chambers 396e, 396f, 396k,396l. On the other hand, in the case where the angle θ of the axis lineA of the upper arm 12 from the axis line O of the arm receiver 14 isnegative, the respective pressures in the air chambers 396a, 396b, 396g,396h provided in the front portion of the receiver 14 are increased.Accordingly, the control device 368 operates for decreasing theinclination angle of the housing 10 and thereby decreasing therespective pressures of those chambers 396a, 396b, 396g, 396h. That is,the control device 368 operates for positioning the housing 10 or armreceiver 14 so that the pressing forces exerted by the upper arm 12 tothe air chambers 396a to 396l are made substantially uniform with oneanother. Consequently, the axis line A of the upper arm 12 issubstantially aligned with the axis line O of the arm receiver 14.

FIG. 22 shows another arm-receiver positioning device 399 which may beemployed for adjusting the height of the housing 10 of the BP apparatus310 from the table 338. The present positioning device 399 includes fouradjustable legs 348 or 380 provided at the four corners of the bottomwall of the housing 10. The control device 368 adjusts the respectiveamounts of advancement of the four legs 348, 380 from the bottom of thehousing 10, all in the same manner using the positioning device 348,352, 354 shown in FIG. 18, or the positioning device 377 shown in FIG.20, in such a manner that the inclination angle of the housing 10relative to the table 2338 is not adjusted but the height of the housing10 from the table 338 is adjusted. In FIG. 22, the first and secondmicroswitches 340, 342 or the air chambers 396 and pressure switches 398are not provided on the inner surface 343 of the arm receiver 14, but anoptical sensor 402 which measures the sitting height of a living subject400 or the height of the subject's shoulder, is provided on the top ofthe outer circumferential surface of the arm receiver 14.

When the subject 400 sits in front of the BP apparatus 310 and insertshis or her arm 12 into the arm receiver 14 for a BP measurement, thecontrol device 368 starts to measure, using the sensor 402, the sittingheight or shoulder's height of the subject 400. Based on the measuredheight, the control device 368 operates to adjust the height of thehousing 10 so that the longitudinal axis line of the upper arm 12 issubstantially aligned with the longitudinal axis line of the armreceiver 14. Assuming that the inclination angle of the arm receiver 14is constant and the length of the upper arm 12 (i.e. length between theelbow and the shoulder) is constant, the control device 368 candetermine, based on the measured sitting or shoulder height of thesubject 400, an appropriate height of the housing 10 which ensures thatthe longitudinal axis line of the upper arm 12 is aligned with thelongitudinal axis line of the arm receiver 14. Data or a maprepresenting a prescribed relationship between the sitting (orshoulder's) heights of the subject 400 and the heights of the housing 10are/is pre-stored in a read only memory (ROM) provided in the controldevice 368. The control device 368 determines, based on a measuredsitting or shoulder's height of the subject 400, a desirable height ofthe housing 10 according to the prescribed relationship. In thearm-receiver positioning device 399, the sensor 402 indirectly measuresthe amount of misalignment of the longitudinal axis line of the upperarm 12 from the longitudinal axis line of the receiver 14.

It is to be understood that the BP apparatus 310 may be modified invarious manners.

For example, while the BP apparatus 310 adjusts the inclination angle orheight of the housing 10 as a whole, it is possible to provide anautomatic cuff winding device including the arm receiver 14, cuff 16,belt 18, etc., outside the housing 10, and place the winding device onthe housing 10. Alternatively, it is possible to provide an automaticcuff winding device, separately from the housing 10, and place thewinding device on the table 338. In the latter cases, the BP apparatus310 may be adapted to adjust the inclination angle of only the windingdevice relative to the housing 10 or table 338, or the height of onlythe winding device from the housing 10 or table 338.

Although the detector 395 shown in FIGS. 21(A), 21(B) includes twelveair chambers 396, it is possible to employ a different number of airchambers 396. For example, the detector 395 may include only the fourair chambers 396a, 396g, 396f, 396l provided at the front and rear endsof the arm receiver 14. The detector 395 essentially needs at least oneair chamber 396 at the front and rear ends of the receiver 14,respectively, i.e., at least two air chambers 396 in total.

In the BP apparatus 310 shown in FIG. 22, it is possible to replace thesensor 402 with the microswitches 340, 342 or the air chambers 396 andpressure switches 398. On the contrary, in the BP apparatus shown inFIGS. 17-20 or the BP apparatus shown in FIGS. 21(A) and 21(B), it ispossible to replace the microswitches 340, 342 or the air chambers 396and pressure switches 398, with the sensor 402. The sensors 340, 342,396, 398, 402 may be replaced with other sorts of pressure sensors whichdetect the pressing of the subject's arm 12.

Although in FIG. 22 the BP apparatus 310 adjusts the height of thehousing 10, the apparatus 310 may further include a device for adjustingthe height of the table 338 on which the apparatus 310 is placed. In thelatter case, the height of the housing 10 can be adjusted.

While the BP apparatus 310 has the detector 340, 342, 396, 398, 402 fordetecting a misalignment of the upper arm 12 from the arm receiver 14,only in a vertical plane, and adjusts the vertical misalignment of theupper arm 12, it is possible that the BP apparatus 310 have a horizontalmisalignment detector for detecting a misalignment of the upper arm 12or the arm receiver 14 in a horizontal plane, and a horizontal adjustingdevice for adjusting the horizontal misalignment of the upper arm 12 orthe arm receiver 14. The horizontal misalignment detector may includemicroswitches provided at the left and right ends of the inner surface343 of the receiver 14. The horizontal adjusting device may include adevice for rotating the housing 10 as a whole, or the automatic cuffwinding device 14, 16, 18, about a vertical axis line extending throughthe elbow rest 344 and perpendicular to the tale 338. In the lattercase, the subject is not required to adjust his or her arm 12 relativeto the arm receiver 14, also in the horizontal plane.

In the BP apparatus 310, it is possible to omit the third microswitch346. In the latter case, however, the BP apparatus 310 needs a start keyoperable for commanding the control device 368 to start, after insertionof the arm 12 into the arm receiver 14, adjusting the position of thereceiver 14.

The arm-receiver positioning device 348, 352, 354 shown in FIG. 18,device 377 shown in FIG. 20, or device 399 shown in FIG. 22 may bereplaced by other sorts of positioning devices; such as a gear devicewhich includes adjustable legs 348 or 380 each having an axial portionwith teeth, i.e., rack portion, a pinion engaged with the rack portionof each leg, and a motor with a reduction gear unit which operates fordirectly advancing and retracting each leg from and into the housing 10.

Referring next to FIG. 23, there is shown a blood pressure (BP) monitorapparatus 500 as a fourth embodiment of the present invention.

In FIG. 23, reference numeral 510 designates an inflatable cuff adaptedto be wound around a body portion (e.g., upper arm) of a living subject(e.g., patient) so as to press the upper arm. The cuff 510 includes aninflatable bag 510a formed of an elastic sheet (e.g., rubber sheet orvinyl sheet), and an inextensible arm belt 510b in which the bag 510a isaccommodated. The bag 510a of the cuff 510 is connected via piping 518to a pressure sensor 512, an air pump 514, and a pressure regulatorvalve 516.

The pressure sensor 512 includes, e.g., a semiconductor pressure sensingelement (not shown) which detects an air pressure in the cuff 510 ("cuffpressure") and supplies a detection signal, SP, to a low-pass filter520, a first band-pass filter 522, and a second band-pass filter 523.The low-pass filter 520 permits only a DC (direct current) orstatic-pressure component of the detection signal SP to passtherethrough, thereby supplying a cuff-pressure signal, SK, representingthe detected static cuff pressure, P_(c), to an analog-to-digital (A/D)converter 524.

The first band-pass filter 522 permits only a 1 to 10 Hz frequency AC(alternating current) component of the detection signal SP to passtherethrough, thereby supplying a first pulse-wave signal, SM1,representing a pulse wave of the subject, to the A/D converter 524. Thepulse wave is produced in the cuff 510 because of the pulsation ofarteries of the upper arm under the cuff 510 in synchronism with theheartbeats of the subject, while the cuff pressure P_(c) is changedwithin an appropriate pressure range. Thus, the pulse wave produced inthe cuff 510 is obtained as the AC component of the detection signal SPsupplied from the pressure sensor 512.

The second band-pass filter 523 permits only a 0.5 to 20 Hz frequency ACcomponent of the detection signal SP to pass therethrough, therebysupplying a second pulse-wave signal, SM2, to the A/C converter 524. Thefirst band-pass filter 522 has a narrow frequency range (e.g., 1 to 10Hz) for obtaining, from the detection signal SP, successive pulseamplitudes free from artifact noise possibly mixed therewith because ofphysical motion of the subject. Pulse amplitudes are pressureoscillations produced in the cuff 510 in synchronism with the heartbeatsof the subject while the cuff pressure P_(c) is slowly changed at a rateof, e.g., 2 to 3 mmHg/sec in measuring a blood pressure (BP) value ofthe subject. On the other hand, the second band-pass filter 523 has acomparatively wide frequency range (e.g., 0.5 to 20 Hz) for obtaining,from the same signal SP, a pulse wave having a waveform similar to thatof a pulse wave which is directly or invasively obtained from inside anartery of the subject. The second band-pass filter 523 is used to obtainthe waveform of a pulse wave while the cuff pressure P_(c) is held at aprescribed value (described later). The A/D converter 524 has a timedivision multiplexer for time sharing of the three analog signals SK,SM1, SM2, and concurrently converts those analog signals to respectivedigital signals. In the present embodiment, the first and secondband-pass filters 522, 523 serve as a pulse wave detector.

The present BP monitor apparatus 500 has an arithmetic control device526 which is essentially constituted by a microcomputer including a CPU528, a RAM 530, a ROM 532, a first output interface 534, and a secondoutput interface 536. The CPU 528 receives the three digital signals SK,SM1, SM2 from the A/D converter 524, and processes those signals byutilizing the temporary-storage function of the RAM 530 and the controlprograms pre-stored in the ROM 532, so that the CPU 528 controls theoperations of the air pump 514 and the regulator valve 516 via the firstoutput interface 534 and controls an output device 538 via the secondoutput interface 536. The output device 538 includes an image displaypanel (e.g., liquid-crystal panel) which has a number of pictureelements and is capable of displaying numerals and curves representingthe measured BP values and the detected pulse-wave waveform of thesubject. The output device 538 may further include a printer, as needed,which records using an ink numerals and curves on a recording sheet.

A mode switch 540 is manually operable for selecting one of asingle-BP-measurement mode and a BP-monitor mode. The mode switch 540selectively supplies one of a first signal indicative of thesingle-measurement mode and a second signal indicative of the monitormode, to the CPU 528. An ON/OFF switch 542 is manually operable forstarting and stopping the present BP monitor apparatus 500, andalternatively supplies a START signal and a STOP signal to the CPU 528upon operation thereof.

Thus, the BP monitor apparatus 500 includes a pulse wave detector (i.e.,first and second band-pass filters 522, 523) for detecting, as a pulsewave, a pressure oscillation produced in the cuff 510 wound around abody portion of a living subject, in synchronism with the heartbeats ofthe subject, while the cuff 510 presses the subject's body portion. TheBP monitor apparatus 500 also includes a BP measuring device 508 whichdetermines a BP value of the subject based on the change of pulseamplitudes, A_(m), which are obtained as the cuff pressure P_(c) ischanged. The BP measuring device 508 includes the elements 510, 512,514, 516, 518, 520, 522, 523, and 526. The control device 526 or CPU 528controls the pressure regular valve 516 for repetitively changing andholding the cuff pressure Pc to and at a prescribed pressure value lowerthan a mean BP value of the subject (hereinafter, this period isreferred to as the "operative period"), in each non-BP-measuring period,T_(2M) (FIG. 27), in which the BP measuring device 508 does not operatefor a BP measurement. A prescribed non-operative period, T_(1M), isinserted between two successive operation periods. The CPU 528 operatesfor determining a rate of change, θ(=ΔA_(m) /ΔP_(c)), of the pulseamplitudes A_(m) with respect to the cuff pressure P_(c). The CPU 528also operates for identifying, based on the determined rate of change θ,whether the subject is suffering an abnormal blood pressure.

In the case where the subject has a normal blood pressure, the BPmonitor apparatus 500 obtains successive pulse amplitudes whose envelopeis shown at solid line in FIG. 29. This envelope has an angle, α,approximating a rate of change θ thereof corresponding to a certain cuffpressure P_(c-1). On the other hand, in the case where the subject issuffering an abnormally low blood pressure, the monitor apparatus 500obtains successive pulse amplitudes whose envelope is shown at one-dotchain line in FIG. 29. This envelope has an angle, β, approximating arate of change θ thereof corresponding to the same cuff pressureP_(c-1). The angle β is significantly greater than the angle α, becausethe respective values of the one-dot-chain-line envelope are slightlysmaller than those of the solid-line envelope and simultaneously theupper peak of the former envelope corresponds to a lower cuff pressurethan a lower cuff pressure to which the upper peak of the latterenvelope corresponds. In view of this fact, the control device 526 orCPU 528 judges that the subject is suffering an abnormally low bloodpressure, if the rate of change θ exceeds a reference value, θ_(o).However, if the subject is in the state of shock, the BP apparatus 500provides successive pulse amplitudes whose envelope is shown at two-dotchain line in FIG. 29. This envelope has an angle, γ, approximating arate of change θ thereof corresponding to the same cuff pressureP_(c-1). The angle γ is smaller than the angle α. However, therespective values of the two-dot-chain-line envelope are significantlysmaller than those of the solid-line envelope. Therefore, the CPU 328further judges whether a detected pulse amplitude is smaller than areference amplitude, Am_(o), and if a positive result or judgment ismade the CPU 328 identifies that the subject is suffering an abnormallylow blood pressure. When the CPU 528 makes a judgment that the subjecthas an abnormal blood pressure, the BP measuring device 508automatically measures a BP value of the subject according to a controlprogram pre-stored in the ROM 532.

The pressure regulator valve 516 is controlled to change the cuffpressure P_(c) from atmospheric pressure to a prescribed pressure level,P_(CH), so that the first band-pass filter 522 detects a plurality ofpulses having different amplitudes A_(m) and the CPU 528 determines,based on the detected pulse amplitudes A_(m), a rate of change θ of thepulse amplitudes A_(m) with respect to the cuff pressure P_(c).Thereafter, the regulator valve 516 is controlled to hold is the cuffpressure P_(c) at the prescribed pressure P_(CH) for a prescribedpressure-hold period, T_(3M), so that the band-pass filter 522 detects apulse wave, or respective pulses of the pulse wave, which are to beutilized for other purposes described below in short and later indetail.

The control device 526 or CPU 528 further judges whether the bloodpressure of the subject is abnormal, based on a pulse magnitude A_(m)detected in a pressure-hold period T_(3M), in a manner described later.When the CPU 528 makes a positive judgment in this manner, the BPmeasuring device 508 immediately starts to carry out a BP measurement onthe subject. Thus, whenever the control device 526 or CPU 528 judgesthat the subject is suffering an abnormal blood pressure, the BPmeasuring device 508 measures a BP value of the subject.

In FIG. 23, reference numeral 546 designates an reference-value inputdevice which is manually operable to input or specify the referencevalues which are to be used by the control device 526 or CPU 528 injudging whether the subject is suffering an abnormal blood pressure. Thecontrol device 526 or CPU 528 further functions to change the prescribedpressure value P_(CH), based on the reference values input through theinput device 546. When the control device 526 or CPU 528 judges that thesubject is suffering an abnormal blood pressure, the output device 538displays that judgment on the image-display panel thereof.

There will be described the operation of the BP monitor apparatus 500constructed as described above, by reference to the flow charts of FIGS.24 and 25. Initially, at Step S101, the CPU 528 judges whether theSTART/STOP switch 542 has been operated for starting the operation ofthe present apparatus 500, based on the START or STOP signal suppliedfrom the switch 542. If a negative judgment is made at Step S101, thecontrol of the CPU 528 waits for receiving the START signal from theswitch 542. Meanwhile, if a positive judgment is made, the controlproceeds with Step S102 to operate the air pump 514 and the pressureregulator valve 516 so as to supply a pressurized air to the inflatablecuff 510 (i.e., bag 510a) and thereby quickly increase the air pressurein the cuff 510, i.e., cuff pressure Pc.

Step S102 is followed by Step S103 to judge whether the cuff pressureP_(c) has reached a prescribed target pressure, P_(CM) (e.g., 180 mmHg).If a negative judgment is made at Step S103, the CPU 528 repeats StepsS102 and S103. Meanwhile, if a positive judgment is made, the control ofthe CPU 528 proceeds with Step S104 to stop the air pump 514 and changethe degree of opening of the pressure regulator valve 516 so as toslowly deflate the cuff 510, i.e., reduce the cuff pressure P_(c). Thisslow cuff deflation is effected at a rate of, e.g., 2 to 3 mmHg/secsuitable for BP measurements. Step S104 is followed by Step S105 tojudge whether the CPU 528 has received a length of first pulse wavesignal SM1 corresponding to one pulse having an amplitude, i.e., onecycle of heartbeat of the subject. If a negative judgment is made atStep S105, the CPU 528 repeats Steps S104 and S105.

Meanwhile, if a positive judgment is made at Step S105, the control ofthe CPU 528 proceeds with Step S106 to operate according to a knownoscillometric BP measurement algorithm, i.e., determine the BP values ofthe subject. Step S106 is followed by Step S107 to judge whether the BPmeasurement subroutine at Step S106 has been completed. While the cuffpressure P_(c) is slowly reduced in the BP measuring period, therespective amplitudes of successive pulses of the pulse wave, i.e.,pulse wave signal SM1 initially increase and then decrease as shown inFIG. 28. The amplitude of one pulse ("pulse amplitude") is obtained bysubtracting the lower-peak magnitude of the one-pulse signal SM1 fromthe upper-peak of the same. In the known oscillometric BP measurementalgorithm, a cuff pressure P_(c) at the time when the pulse amplitudessignificantly greatly increase is determined as a systolic BP value,P_(sys), of the subject; a cuff pressure P_(c) at the time of detectionof the greatest pulse amplitude is determined as a mean BP value,P_(mean) ; and a cuff pressure P_(c) at the time when the pulseamplitudes significantly greatly decrease is determined as a diastolicBP value, P_(dia).

If a negative judgment is made at Step S107, the CPU 528 repeats StepsS104 through S107. Meanwhile, if a positive judgment is made at StepS107, the control of the CPU 528 proceeds with Step S108 to store thethree BP values P_(sys), P_(mean), P_(dia) in the RAM 530 and displaythose BP values in digits on the image-display panel of the outputdevice 538. At the following Step S109, the CPU 528 fully opens thepressure regulator valve 516 so as to quickly deflate the cuff 510,i.e., quickly decrease the cuff pressure P_(c) and thereby release thesubject's upper arm from the cuff pressure P_(c). In the presentembodiment, Steps S102 to S109 serve as a part of the BP measuringdevice 508 that automatically carries out a BP measurement in a seriesof prescribed steps.

Step S109 is followed by Step S110 to determine a relationship betweenBP values, P_(BP), and pulse amplitudes A_(m) which relationship isutilized at Step S124 described later. Specifically, the CPU 528determines a first P_(BP) -A_(m) relationship based on the BP valueP_(sys) and the pulse amplitude A_(m) corresponding to the cuff pressureP_(c) determined as the BP value P_(sys), and a second P_(BP) -A_(m)relationship based on the BP value P_(dia) and the pulse amplitude A_(m)corresponding to the cuff pressure P_(c) determined as the BP valueP_(dia). The first or second P_(BP) -A_(m) relationship may be definedby the following linear expression: P_(BP) =K₁ ×A_(m) +K₂, where K₁ andK₂ are constants, as shown in FIG. 26. This linear expression defines aP_(BP) -A_(m) relationship proper to the specific living subject. Theconstant K₂ may be a prescribed value, or zero.

At the following Step S111, the CPU 528 judges whether the BP monitorapparatus 500 is currently placed in the BP-monitor mode, based on amode signal supplied from the mode switch 540. If a negative judgment ismade at Step S111, that is, if the apparatus 500 is currently placed inthe single-BP-measurement mode, the current control cycle of the CPU 528in accordance with this main routine is ended, and the control of theCPU 528 returns to Step S101 and the following steps. On the other hand,if a positive judgment is made at Step S111, that is, if the apparatus500 is currently placed in the BP-monitor mode, the control of the CPU528 goes to Step S112 and the following steps, i.e., BP monitorsubroutine. The CPU 528 repeats Steps S113 through S128 at a prescribedperiod of time, T_(1M) (e.g., 1 to 3 minutes).

At Steps S112 and S113, the CPU 528 clears the contents of a second anda first time counter (i.e., timers) T2 and T1, respectively. Step S113is followed by Step S114 to increment the contents of the two timers T1,T2 each by one, i.e., T1←T1+1 and T2←T2+1. At the following Step S115,the CPU 528 judges whether the contents of the first timer Ti hasreached the prescribed time period T_(1M). Each time the first timer T1counts up the reference time T_(1M), the CPU 528 controls the air pump514 and the regulator valve 516 to increase the cuff pressure P_(c) upto the hold pressure P_(CH) so as to monitor the blood pressure of thesubject.

Shortly after the beginning of the BP monitor operation, negativejudgments are made at Step S115, so that the CPU 528 repeats Steps S114and S115. Meanwhile, if a positive judgment is made at Step S115, thecontrol of the CPU 528 proceeds with Step S116 to operate the air pump514 and the regulator valve 516 to slowly increase the cuff pressureP_(c). The rate of increasing of the cuff pressure P_(c) ispre-determined at, e.g., 3 mmHg/sec so that the BP monitor apparatus 500can obtain at least three pulses before the cuff pressure P_(c) israised up to the hold pressure P_(CH).

Step S116 is followed by Step S117 to detect each pulse which occursduring the slow increasing of the cuff pressure P_(c) and store theamplitude A_(m) of each detected pulse in an appropriate area of the RAM530. In addition, the CPU 528 determines a straight line approximatingthe detected at least three pulse amplitudes A_(m). As shown in FIG. 28,this straight line fits to a low-pressure-side portion of the envelopeof the subject's pulse amplitudes A_(m) obtained in the BP measuringperiod at Step S106. On the approximation line, the CPU 528 determines arate of change θ(=ΔA_(m) /ΔP_(c)) of the pulse amplitudes A_(m) withrespect to the cuff pressure P_(c), based on prescribed cuff pressurevalues P_(c-1) and P_(c-2), according to the following expression (1):

    θ=(A.sub.m2 -A.sub.m1)/(P.sub.c-2 -P.sub.c-1)        (1)

where A_(m1) and A_(m2) are respective pulse amplitudes corresponding tothe cuff pressure values P_(c-1), P_(c-2) on the approximation line.

In the present embodiment, Step S117 and a portion of the control device526 for carrying out this step cooperate with each other to serve asmeans for determining a rate of change of pulse amplitudes A_(m) withrespect to cuff pressure P_(c).

Step S117 is followed by Step S118 to judge whether the determined rateof change θ is greater than a reference value θ₀. The reference value θ₀corresponds to the angle β obtained on the low-pressure-side portion ofthe envelope (indicated at one-dot-chain line in FIG. 29) of the pulseamplitudes of a living subject suffering abnormally low blood pressurevalues, e.g., 90 mmHg systolic BP value and 50 mmHg diastolic BP value.If a positive judgment is made at Step S118, the control of the CPU 528goes to Step S119 to operate the output device 438 to indicate that thesubject's blood pressure is abnormal. Following Step S119, the controlof the CPU 528 returns to Step S102 and the following steps toimmediately measure a BP value of the subject at the time ofidentification of the subject's BP abnormality.

On the other hand, if a negative judgment is made at Step S118, thecontrol of the CPU 528 goes to Step S120 to judge whether each pulseamplitude A_(m) is greater than a reference value A_(m0). The referencevalue A_(m0) corresponds to the angle γ obtained on thelow-pressure-side portion of the envelope vindicated at two-dot-chainline in FIG. 29) of the pulse amplitudes of a living subject who iscurrently in the state of shock. If a negative judgment is made at StepS120, the control of the CPU 528 goes to Step S119 to control the outputdevice 438 to indicate that the subject is in the state of shock.Following Step S119, the control of the CPU 528 returns to Step S102 andthe following steps to immediately measure a BP value of the subject atthe time of identification of the subject's shock state. In the presentembodiment, Steps S118 and S120 and a portion of the control device forcarrying out these steps cooperate with each other to serve as firstabnormality judging means for identifying a blood pressure abnormalityof a living subject.

On the other hand, if a positive judgment is made at Step S120, thecontrol of the CPU 528 goes to Step S121 to judge whether the cuffpressure P_(c) has reached the prescribed hold pressure P_(CH). The holdpressure P_(CH) is pre-determined to fall within a range of 20 to 30mmHg which is adequately lower than the mean BP value P_(mean) of thesubject and which ensures that the BP monitor apparatus 500 detects atime change of the pulse amplitudes A_(m). If a negative judgment ismade at Step S121, the control of the CPU 528 goes back to Step S116 andthe following steps. Meanwhile, if a positive judgment is made, thecontrol goes to Step S122 to stop the slow increasing of the cuffpressure P_(c) and temporarily hold the cuff pressure P_(c) at the holdpressure P_(CH) for the prescribed pressure-hold period T_(3M), forexample, 2 seconds.

Step S122 is followed by Step S123 to read in a pulse A_(mh) detectedwhile the cuff pressure P_(c) is held at the hold pressure P_(CH). Atthe following Step S124, the CPU 528 estimates a systolic and adiastolic BP value, P_(sysE) and P_(diaE), of the subject, based on theread-in pulse amplitude A_(mh), according to the first and second PBP-Amrelationships determined at Step S110.

At the following Step S125, the CPU 528 judges whether the estimatedsystolic BP value P_(sysE) is smaller than a reference value, P_(sysE0),or whether the estimated diastolic BP value P_(diaE) is smaller than areference value, P_(diaE0). These reference values P_(sysE0), P_(diaE0)are employed for monitoring an abnormal decrease or fall of the bloodpressure of the subject, and are pre-determined at, e.g., 90 mmHg and 50mmHg, respectively. If a positive judgment is made with respect to atleast one of the two questions at Step S125, the control of the CPU 528goes to Step S126 to operate the output device 538 to indicate anabnormal decrease of the subject's blood pressure. Then, the control ofthe CPU 528 returns to Step S102 and the following steps to measure a BPvalue of the subject at the time of detection of the abnormal BPdecrease.

On the other hand, if a negative judgement is made with respect to boththe two questions of Step S125, the control of the CPU 528 goes to StepS127 to deflate the cuff 510, i.e, reduce the cuff pressure P_(c) toatmospheric pressure, thereby releasing the subject's upper arm from thepressing of the cuff 510 held at the hold pressure P_(CH). Step S127 isfollowed by Step S128 to judge whether the contents of the second timerT2 has reached a prescribed reference value T_(2M). This reference valueT_(2M) is a regular interval of time at which the control device 526periodically carries out Steps S102 and the following steps, and ispre-selected at a time of 10 to 30 minutes. Shortly after the beginningof the BP monitor operation, negative judgments are made at Step S128,so that the CPU 528 carries out Steps S113 and the following steps.Meanwhile, if a positive judgment is made at Step S128, the control ofthe CPU 528 goes back to Step S102 and the following steps.

When the BP monitor apparatus 500 is operated according to the flowcharts of FIGS. 24 and 25, the cuff pressure P_(c) changes as shown inFIG. 27. In the BP monitor period, i.e., non-BP-measuring periodfollowing the BP-measuring period effected in response to the startingoperation of the ON/OFF switch 540, the CPU 528 periodically operatesfor slowly increasing the cuff pressure P_(c) up to the prescribed holdpressure P_(CH), while alternately inserting the prescribed intervaltime T_(1M) between successive two pressure-hold periods T_(3M). The CPU528 determines a rate of change θ of the pulse amplitudes A_(m) obtainedduring the slow increasing of the cuff pressure P_(c), and judges, basedon the determined rate of change θ, whether the subject is suffering anabnormally low blood pressure. In addition, the CPU 528 judges whetherthe subject is suffering an abnormal blood pressure decrease or fallbecause of being in the state of shock. Furthermore, the CPU 528estimates, based on the pulse amplitude A_(mh) detected during thepressure-hold period T_(3M), the systolic and diastolic BP valuesP_(sysE), P_(diaE) and judges whether the subject is suffering anabnormally low blood pressure, based on the estimated BP valuesP_(sysE), P_(diaE).

It emerges from the foregoing description that in the fourth embodiment,the CPU 528 determines a rate of change θ of the pulse amplitudes A_(m)with respect to the cuff pressure P_(c), each time the CPU 528 operatesthe air pump 514 and regulator valve 516 to slowly increase, following aprescribed interval T_(1M), the cuff pressure P_(c) from atmosphericpressure to the prescribed pressure P_(CH) lower than the mean BP valueP_(mean) of a living subject. The CPU 528 judges, based on thedetermined rate of change θ, whether the subject is suffering a bloodpressure abnormality. Thus, in the present embodiment, the BP monitorapparatus 500 utilizes, for monitoring the blood pressure of thesubject, the phenomenon that the rate of change θ of thelow-pressure-side portion of the envelope representing the change of thepulse amplitudes A_(m) with respect to the cuff pressure P_(c), changesas the blood pressure of the subject changes. Therefore, the BPmonitoring of the apparatus 500 is carried out with high reliability.Since the rate of change θ is determined based on the data obtainedwhile the cuff pressure P_(c) is changed in a low pressure range fromatmospheric pressure to the hold pressure P_(CH), the BP monitoroperation of the apparatus 500 does not cause the subject to feeldiscomfort due to the pressing of the inflated cuff 510.

Furthermore, the BP measuring device 508 automatically measures BPvalues of the subject in a series of prescribed steps, each time thecontrol device 526 or CPU 528 identifies that the subject is suffering ablood pressure abnormality. Thus, the BP measuring device 528 reliablymeasures the BP values of the subject immediately after theidentification of the blood pressure abnormality. The thus obtained BPvalues of the subject ensure that medical workers such as doctors makeappropriate treatments with the subject.

When a living subject is in a shock state, the envelope representing thechange of the pulse amplitude A_(m) with respect to the cuff pressureP_(c), becomes more or less flat. Therefore, in this case, it is verydifficult for the BP apparatus 500 to make an abnormality judgment basedon the rate of change θ of the pulse amplitude A_(m) with respect to thecuff pressure P_(c). However, the CPU 528 also judges whether the pulseamplitude A_(m) detected during the slow increasing of the cuff pressureP_(c) is smaller than the reference value A_(m0). If the pulse amplitudeA_(m) is smaller than the reference value A_(m0), the CPU 528 judgesthat the subject is suffering an abnormal blood pressure fall, therebyeasily identifying that the subject is in the state of shock.

In the BP monitor apparatus 500, the control device 526 or CPU 528controls the air pump 514 and the pressure regulator valve 516 to changethe cuff pressure P_(c) to the prescribed hold pressure P_(CH) and thenhold the cuff pressure P_(c) at the pressure level P_(CH) for theprescribed period T_(3M). Based on the pulse amplitude A_(mh) obtainedduring the pressure-hold period T_(3M), the CPU 528 finds the subject'sblood pressure abnormality. Therefore, the BP monitoring of the presentapparatus 500 is carried out with high reliability.

Thus, in the present embodiment, whenever the control device 526 or CPU528 finds a blood pressure abnormality of a living subject, the BPmeasuring device 508 automatically measures BP values of the subject.Therefore, the reliability of the BP monitoring of the apparatus 500 isimproved as such.

It is to be understood that the BP monitor apparatus 500 may be modifiedin various ways.

For example, FIG. 30 shows a flow chart representing steps which may becarried out in place of Step S117 of FIG. 25 by the control device 526or CPU 528. The steps of FIG. 30 serve as a subroutine for determining arate of change θ of pulse amplitudes A_(m).

At Step S117-1, the CPU 528 controls the air pump 514 and the regulatorvalve 516 to hold the cuff pressure P_(c) at a first hold pressureP_(CH1). The first hold pressure P_(CH1) is pre-selected at a valuewhich ensures that the monitor apparatus 500 obtains pulse amplitudesA_(m) suitable for determining a rate of change θ of the pulseamplitudes A_(m) on the low-pressure-side portion of the envelope of thepulse amplitudes A_(m) shown in FIG. 28, and may be pre-determined tofall within a range of 15 to 20 mmHg. Step S117-l is followed by StepS117-2 to judge whether the respective amplitudes of two successivepulses are substantially equal to each other. This step is provided forthe purpose of discarding noise. Since the cuff pressure P_(c) is notchanged at Step S117-2 (and also at Step S117-5 (described later)), theCPU 528 reads in the second pulse wave signal SM2 that has been filteredthrough the second band-pass filter 523 and is more accurate than thefirst pulse wave signal SM1. If a negative judgment is made at StepS117-2, the CPU 528 repeats Steps S117-1 and S117-2. On the other hand,if a positive judgment is made at Step S117-2, the control of the CPU528 proceeds with Step S117-3 to store, as a first pulse amplitude,A_(m1), the two pulse amplitudes substantially equal to each other, inthe RAM 530.

At the following Step S117-4, the CPU 528 controls the air pump 514 andthe regulator valve 516 to increase and hold the cuff pressure P_(c) toand at a second hold pressure P_(CH2). The second hold pressure P_(CH2)is pre-selected at a value which ensures that the monitor apparatus 500obtains pulse amplitudes A_(m) greater than the pulse amplitude Am1stored at Step S117-3 and suitable for determining the rate of change θon the low-pressure-side portion of the envelope of the pulse amplitudesA_(m) shown in FIG. 28, and may be pre-determined to fall within a rangeof 25 to 30 mmHg. Step S117-4 is followed by Step S117-5 to judgewhether the respective amplitudes of two successive pulses aresubstantially equal to each other. If a negative judgment is made atStep S117-2, the CPU 528 repeats Steps S117-4 and S117-5. On the otherhand, if a positive judgment is made at Step S117-5, the controlproceeds with Step S117-6 to store, as a second pulse amplitude, A_(m2),the two pulse amplitudes substantially equal to each other, in the RAM530.

At the following Step S117-7, the CPU 528 calculates the rate of changeθ from the first and second hold pressure values P_(CH1), P_(CH2) andthe first and second pulse amplitude values A_(m1), A_(m2), according tothe following expression (2):

    θ=(A.sub.m2 -A.sub.m1)/(P.sub.CH2 -P.sub.CH1)        (2)

FIG. 31 shows a time change of cuff pressure P_(c) when the monitorapparatus 500 operates according to the flow chart of FIG. 30.Specifically described, the cuff pressure P_(c) is stepwise increased upto the first hold pressure P_(CH1), and the first hold pressure P_(CH1)is maintained until two successive pulses having equal amplitudes areobtained and the first pulse amplitude A_(m1) is stored. Subsequently,the cuff pressure P_(c) is stepwise increased from the first holdpressure P_(CH1) to the second hold pressure P_(CH2), and the secondhold pressure P_(CH2) is maintained until two successive pulses havingequal amplitudes are obtained and the second pulse amplitude A_(m2) isstored. The second hold pressure P_(CH2) may be equal to the holdpressure P_(CH) used as a reference pressure value at Step S121 of FIG.25. In the latter case, Steps S121 and S122 are omitted from the flowchart of FIG. 25, and at Step S124 the CPU 528 estimates, based on thesecond pulse amplitude A_(m2), the systolic and diastolic BP valuesP_(sysE), P_(diaE) of the subject.

This modified control manner enjoys the same advantages as those withthe control manner in accordance with the flow charts of FIGS. 24 and25. Additionally, since the rate of change θ of the low-pressure-sideincreasing portion of the pulse-amplitude envelope is calculated basedon the first and second pulse amplitudes A_(m1), A_(m2) obtained at theprescribed first and second hold pressures P_(CH1), P_(CH2), thecalculated rate of change θ enjoys a high accuracy and accordingly theaccuracy of monitoring of the present apparatus 500 is improved.Moreover, since the apparatus 500 stores and utilizes the equalamplitude of two successive pulses obtained at the prescribed cuffpressure P_(CH1) or P_(CH2), noise which is possibly mixed withheartbeat-synchronous pulses can effectively be removed or omitted, sothat the accuracy of monitoring of the apparatus 500 is more improved.Furthermore, in the case where the second hold pressure P_(CH2) is equalto the hold pressure P_(CH), the second pulse amplitude Am₂ may be usedfor identifying a subject's blood pressure abnormality at Step S124 ofFIG. 25. Thus, the pressure-hold periods T_(3M) and Steps S121 and S122may be omitted.

FIG. 32 shows a flow chart including steps which may be carried out inaddition to the steps of the flow charts of FIGS. 24 and 25 by themonitor apparatus 500. According to this flow chart, the control device526 or CPU 528 changes the hold pressure P_(CH) or the second holdpressure P_(CH2) based on a reference value θ₀, or reference valueP_(sysE0) or P_(diaE0), which is input through operation of thereference-value input device 546. The input device 546 has three keysfor inputting or specifying a reference value θ₀, a reference valueP_(sysE0), and a reference value P_(diaE0), respectively, each of whichis selected by a medical worker such as a doctor. At Step SA101, the CPU528 reads in a reference value θ₀, P_(sysE0), P_(diaE0) input throughthe input device 546, and updates the prior reference value θ₀,P_(sysE0), P_(diaE0) stored in the RAM 530, by replacing the prior valuewith the newly input value. Step SA101 is followed by Step SA102 todetermine a new hold pressure P_(CH) or a new second hold pressureP_(CH2), based on the new reference value θ₀, P_(sysE0), P_(diaE0),according to a map shown in FIG. 33. This map defines a prescribedrelationship between reference value θ₀, P_(sysE0), or P_(diaE0) andhold pressure P_(CH) or P_(CH2). Although only a single map is shown inFIG. 33, three different maps are, in fact, used for respectiverelationships between three sorts of reference values θ₀, P_(sysE0),P_(diaE0) and hold pressure P_(CH) (or second hold pressure P_(CH2)). Inthis modified control manner, Step SA102 and a portion of the controldevice 526 for carrying out this step cooperate with each other to serveas means for changing the hold pressure P_(CH) or second hold pressureP_(CH2). This modified control manner enjoys the advantage that the holdpressure P_(CH) or second hold pressure P_(CH2) is made as low aspossible and accordingly the discomfort which the subject may feel dueto the cuff pressure P_(c) in the BP monitor mode is minimized.

Although in the fourth embodiment the rate of change θ of pulseamplitudes A_(m) with respect to cuff pressure P_(c) is determinedaccording to the expression (1) or (2), it is possible to determine, asa rate of change θ, a maximum rate of change, (dA_(m) /dP_(c))_(max), ofan increasing portion of the pulse-amplitude envelope shown in FIG. 28which portion is defined as a portion from the smallest pulse amplitude(i.e., lower peak) to the greatest pulse amplitude (i.e., upper peak).

While the BP monitor apparatus 500 holds the cuff pressure P_(c) at thehold pressure P_(CH) in each pressure-hold period T_(3M), it is possibleto omit the pressure-hold periods T_(3M). That is, the BP monitorapparatus 500 may be modified not to operate for identifying a subject'sblood pressure abnormality based on a pulse amplitude obtained in eachpressure-hold period T_(3M).

In the case where the hold pressure P_(CH) or the second hold pressureP_(CH2) is pre-selected at a prescribed value, the prescribed value isby no means limited to the exemplified pressure range of 20 to 30 mmHg,but may be selected with some effect at any value lower than a mean BPvalue P_(mean) of a living subject. The prescribed value may be selectedat a value lower than a diastolic BP value P_(dia) of the subject, withmore effect, because the blood flow of the subject is not stopped underthe cuff pressure P_(c) held at the selected value.

While the monitor apparatus 500 obtains a pulse wave, i.e., respectivepulses of the pulse wave via the first or second band-pass filter 522,523 from the blood pressure cuff 510, it is possible to employ anothercuff or inflatable bag different from the cuff 510 and detect a pulsewave as a pressure oscillation produced in the different cuff or bag.

Referring next to FIG. 34, there is shown an automatic blood pressure(BP) measuring apparatus 600 as a fifth embodiment of the presentinvention. The BP measuring apparatus 600 has the function of estimatinga blood pressure value of a living subject.

The BP measuring apparatus 600 has a construction similar to that of theBP monitor apparatus 500 shown in FIG. 23. Therefore, the same referencenumerals as used in FIG. 23 are used to designate the correspondingelements or parts of the BP apparatus 600 shown in FIG. 34, and thedescription of those elements or parts is omitted. However, the BPapparatus 600 does not have the reference-value input device 546, andhas a RAM 630 having three memory areas 644, 646, 680 (described later),in place of the RAM 530.

The BP measuring apparatus 600 includes a pressure sensor 512 and alow-pass filter 520 which provide a static pressure in an inflatablecuff 510 ("cuff pressure, P_(c) ") wound around a body portion (e.g.,upper arm) of a living subject; a BP measuring device 508 whichdetermines a BP value or values of the subject based on the change ofrespective amplitudes of pulses of a pulse wave as a pressureoscillation produced in the cuff 510 while the cuff pressure P_(c) isslowly decreased; and an electric air pump 514 and a pressure regulatorvalve 516 which are controlled to start a BP measuring operation byquickly increasing the cuff pressure P_(c) up to a target pressure,P_(CM), and subsequently slowly decreasing the same P_(c) from thetarget pressure P_(CM), and to reduce the cuff pressure P_(c) down toatmospheric pressure after a BP value or values of the subject has orhave been determined during the slow decreasing of the cuff pressureP_(c). A first band-pass filter 522 provides a waveform of a pulse of apulse wave ("pulse waveform") produced in the cuff 510 while the cuffpressure P_(c) is quickly increased. An arithmetic and control device526 or a CPU 528 thereof operates for determining, based on (a) thepulse waveform provided by the band-pass filter 523 during the BPmeasuring operation of the BP measuring device 508 and (b) the BP valueor values determined by the BP measuring device 508, a relationshipbetween pulse waveform, cuff pressure P_(c), and blood pressure whichrelationship is proper to the living subject. The control device 526 orCPU 528 additionally functions for estimating, according to the thusdetermined relationship, a BP value or values of the subject, based on(a) a pulse waveform actually supplied from the first band-pass filter522 and (b) a cuff pressure P_(c) at the time of supplying of the pulsewaveform.

The waveform of one pulse of a pulse wave produced in the form of apressure oscillation in the cuff 510 in synchronism with one cycle ofheartbeat of a living subject, changes as the cuff pressure P_(c)changes from a value around a systolic BP value, P_(sys), of thesubject, to a value around a mean blood pressure P_(mean) of the same,and to a diastolic BP value, P_(dia), of the same. FIGS. 35(A), 35(B),and 35(C) shows three waveforms of one pulse obtained at three cuffpressure values P_(c) generally corresponding to systolic, mean, anddiastolic BP values P_(sys), P_(mean), P_(dia), respectively. As can beunderstood from the three waveforms shown in FIGS. 35(A), 35(B), and35(C), the changing of a pulse waveform means that variouscharacteristics of the pulse waveform change. Those waveformcharacteristics include a maximum slope of an increasing portion of thepulse waveform obtained in a time period, T_(ds) (FIG. 39); a height ofa primary peak of the pulse waveform, i.e., pulse amplitude; a positionand a shape of a secondary peak of the pulse waveform, etc.. Therefore,the CPU 528 determines in advance a relationship between (a) evaluatedvalues of a waveform characteristic, (b) values of cuff pressure P_(c),and (c) values of blood pressure and estimates, according to therelationship, a BP value of the subject based on an evaluated value of acharacteristic of a pulse waveform actually supplied during the quickincreasing of the cuff pressure P_(c) and a cuff pressure value P_(c) atthe time of supplying of the pulse waveform.

In addition, the control device 526 or CPU 528 operates for determining,based on an estimated BP value of the subject, a target pressure valueP_(CM) to which the cuff pressure P_(c) is quickly increased for a BPmeasurement. The CPU 528 controls the air pump 514 and the pressureregulator valve 516 to slowly decrease the cuff pressure P_(c) after thecuff pressure P_(c) has been raised up to the target pressure P_(CM).The CPU 528 also operates for identifying a subject's blood pressureabnormality by comparing the estimated BP value with a reference value.If the subject's abnormal blood pressure is identified, the CPU 528controls an output device 538 to indicate that the blood pressure of thesubject is abnormal.

Hereinafter, there will be described the operation of the BP measuringapparatus 600 constructed as described above, by reference to the flowcharts of FIGS. 36 and 37. First, at Step SA201, the CPU 528 judgeswhether a START/STOP switch 542 has been operated for starting theoperation of the present apparatus 600, based on a START or a STOPsignal supplied from the switch 542. If a negative judgment is made atStep SA201, the control of the CPU 528 waits for receiving the STARTsignal from the switch 542. Meanwhile, if a positive judgment is made,the control proceeds with Step SA202 to operate the air pump 514 and theregulator valve 516 so as to supply a pressurized air to the cuff 510(i.e., bag 510a) and thereby quickly increase the air pressure in thecuff 510, i.e., cuff pressure P_(c) at a rate of about 30 to 40mmHg/sec.

Step SA202 is followed by Step SA203 to judge whether the cuff pressureP_(c) has reached an initial target pressure P_(CM) prescribed at, e.g.,180 mmHg. If a negative judgment is made at Step SA203, the CPU 528repeats Steps SA202 and SA203. Meanwhile, if a positive judgment ismade, the control of the CPU 528 proceeds with Step SA204 to stop theair pump 514 and change the degree of opening of the regulator valve 516so as to slowly deflate the cuff 510, i.e., reduce the cuff pressureP_(c). This slow cuff deflation is carried out at a rate of, e.g., 2 to3 mmHg/sec suitable for BP measurements. Step SA204 is followed by StepSA205 to judge whether the CPU 528 has received a length of first pulsewave signal SM1 corresponding to one pulse, i.e., one cycle of heartbeatof the subject. If a negative judgment is made at Step SA205, the CPU528 repeats Steps SA204 and SA205.

Meanwhile, if a positive judgment is made at Step SA205, the control ofthe CPU 528 proceeds with Step SA206 to store, in a waveform memory area644 of the RAM 630, the waveform of the one-pulse signal SM1 suppliedfrom the first band-pass filter 522. Step SA206 is followed by StepSA207 where the control device 526 or CPU 528 operates according to aknown oscillometric BP measurement algorithm, i.e., determine actual BPvalues of the subject. Step SA207 is followed by Step SA208 to judgewhether the BP measurement subroutine at Step SA207 has been completed.While the cuff pressure P_(c) is slowly reduced, the respectiveamplitudes of successive pulses of the pulse wave, i.e., pulse wavesignal SM1 initially increase and then decrease as shown in FIG. 38. Inthe known oscillometric BP measurement algorithm, a cuff pressure P_(c)at the time when the pulse amplitudes significantly greatly increase isdetermined as a systolic BP value, P_(sys), of the subject; a cuffpressure P_(c) at the time of detection of the greatest pulse amplitudeis determined as a mean BP value, P_(mean) ; and a cuff pressure P_(c)at the time when the pulse amplitudes significantly greatly decrease isdetermined as a diastolic BP value, P_(dia).

If a negative judgment is made at Step SA208, the CPU 528 repeats StepsSA204 through SA208. Meanwhile, if a positive judgment is made at StepSA208, the control of the CPU 528 proceeds with Step SA209 to store thethree BP values P_(sys), P_(mean), P_(dia) in a BP memory area 646 ofthe RAM 630 and display those BP values in digits on an image-displaypanel of the output device 538. At the following Step SA210, the CPU 528fully opens the pressure regulator valve 516 so as to quickly deflatethe cuff 510, i.e., quickly decrease the cuff pressure P_(c) down toatmospheric pressure and thereby release the subject's upper arm fromthe cuff pressure P_(c). In the present embodiment, Steps SA204 to SA208serve as part of the BP measuring device 508 that automatically carriesout a BP measurement.

At the following Step SA211, the CPU 528 judges whether a flag, F_(k),is currently set at one, i.e., F_(k) =1. The state of F_(k) =1 indicatesthat a relationship used for estimating a BP value of the subject hasbeen determined. Upon initialization of the present BP apparatus 600,the flag F_(k) is reset to zero, i.e., F_(k) =0. For a while followingthe starting of operation of the BP apparatus 600, negative judgmentsare made at Step SA211, and the control of the CPU 528 proceeds withStep SA212 to determine, for the subject around an upper arm of whom thecuff 510 is wound, a relationship between (a) evaluated values of awaveform characteristic, (b) values of cuff pressure P_(c) and (c)values of blood pressure. Step SA212 is followed by Step SA213 to setthe flag F_(k) to F_(k) =1. Once the flag F_(k) has been set to F_(k) =1in a certain control cycle, a positive judgment is made at Step SA211 inthe next and following control cycles, so that the control of the CPU528 proceeds with Step SA214 by bypassing Steps SA212 and SA213.

At Step SA212, the control device 526 or CPU 528 evaluates the waveformof each of the respective pulses stored in the waveform memory area 644at Step SA206, with respect to each of various waveform characteristicssuch as pulse amplitude, Amp-b; evaluated value, SLOPE; evaluated value,% MAP; increasing-portion percentage, % IPP; and peak index, PI. Asshown in FIG. 39, the pulse amplitude Amp-b of a pulse waveform isdefined as the difference between the upper and lower peaks of the pulsewaveform (i.e., difference obtained by subtracting the lower peakmagnitude, DAP, from the upper peak magnitude, SAP). That is, the pulseamplitude Amp-b evaluates the height of the pulse waveform. Theevaluated value SLOPE is defined as the maximum differential,(dP/dt)_(max), of an increasing portion of a pulse waveform, i.e., thegreatest slope of the increasing portion of the waveform. The value %MAP is defined as the percentage (=100×a/b ) of the y coordinate (i.e.,height, a) of the barycentric coordinates of the area bounded by a pulsewaveform and a base line extending parallel to the X axis (i.e., "time"axis) and passing through the lower peak, DAP, of the pulse waveform,with respect to the pulse amplitude b (Amp-b). The value % MAP evaluatesthe degree of sharpness of the waveform. The increasing-portionpercentage % IPP is defined as the percentage (=100×T_(ds) /T ) of atime duration, T_(ds), of the increasing portion of a pulse waveformwith respect to a cyclic period, T (sec), of the pulse waveform. Thevalue % IPP evaluates the degree of imbalance of the waveform. The peakindex PI is defined as the percentage (=100×T_(sh) /T ) of a timeduration, T_(sh), between the upper peak, SAP, and the secondary peak ofa pulse waveform, with respect to the cyclic period T (sec) of the pulsewaveform. The evaluated value PI indicates the position of the secondarypeak on the pulse waveform.

At Step SA212, the CPU 528 obtains, from the evaluated values of thewaveform characteristics Amp-b, SLOPE, % MAP, % IPP, PI, datarepresenting a relationship between the measured BP values of thesubject and each waveform characteristic as shown in FIG. 40. Since theBP values P_(sys), P_(mean), P_(dia) of the subject are measured byreading the cuff pressure values P_(c), the CPU 528 can determine arelationship between blood pressure BP, each waveform characteristicAmp-b, SLOPE, % MAP, % IPP, PI, and cuff pressure P_(c) as shown inFIGS. 41, 42, 43, 44, and 45 where the blood pressure BP is variable asa parameter. Although only three curves each representing a BP value areshown in each of FIGS. 41-45, a number of curves each representing a BPvalue are, in fact, employed in each graph or map. Each map contains anumber of base curves given according to a prescribed rule, and thosebase curves are modified based on a measured BP value of the subjectwhich may be one of the measured systolic, mean, and diastolic BP valueP_(sys), P_(mean), P_(dia).

Step SA213 is followed by Step S214 to judge whether the BP monitorapparatus 600 is currently placed in the BP-monitor mode, based on amode signal supplied from a mode switch 540. If a negative judgment ismade at Step S214, that is, if the apparatus 600 is currently placed inthe single-BP-measurement mode, the current control cycle in accordancewith the main routine is ended, and the control of the CPU 528 returnsto Step SA201 and the following steps. On the other hand, if a positivejudgment is made at Step SA214, that is, if the apparatus 500 iscurrently placed in the BP-monitor mode, the control of the CPU 528 goesto Step SA215 to clear the contents of a time counter (timer), T3, tozero and subsequently to Step SA216 to judge whether the START/STOPswitch 542 has been operated again, based on the START/STOP signalsupplied from the switch 542. If a positive judgment is made at StepSA216, the current control cycle is ended, and the control of the CPU528 goes back to Step SA201.

On the other hand, if a negative judgment is made at Step SA216, thecontrol goes to Step SA217 to increment the contents of the timer T3 byone, i.e., T3←T3+1. At the following Step SA217, the CPU 528 judgeswhether the contents of the timer T3 has reached a prescribed referencetime T_(4M). This reference time T_(4M) is the period of cyclicmeasurements of the BP measuring apparatus 600, and is pre-selected tofall within a range of several minutes to several tens of minutes. For awhile following the beginning of the BP monitor operation, negativejudgments are made at Step SA218, so that the CPU 528 repeats StepsSA216, SA217 and SA218. Meanwhile, if a positive judgment is made atStep SA218, the control of the CPU 528 proceeds with Step SA219 and thefollowing steps to estimate a BP value of the subject based on thewaveform of a pulse obtained in a quick inflation of the cuff 510.

More specifically described, at Step SA219, the CPU 528 operates, likeat Step SA202, the air pump 514 and the pressure regulator valve 516 toquickly increase the cuff pressure P_(c). Step SA219 is followed by StepSA220 to judge whether a length of the pulse wave signal SM1corresponding to a cycle of heartbeat of the subject, i.e., the waveformof one pulse is supplied to the control device 526 or CPU 528. If anegative judgment is made at Step SA220, the CPU 528 repeats Steps SA219and SA220 to quickly increase the cuff pressure P_(c). Meanwhile, if apositive judgment is made, the control of the CPU 528 goes to Step SA221to store the waveform of the one-pulse signal SM1 in the waveform memoryarea 644 of the RAM 630.

At the following Step SA222, i.e., BP estimation subroutine, the CPU 528estimates a BP value of the subject, based on the pulse waveform storedin the memory 644 at Step SA221, according to the various relationshipsdetermined at Step SA212 that are proper to the subject around an upperarm of whom the cuff 510 is currently wound. Specifically, at StepSA222, the CPU 528 calculates one or more of characteristic evaluatedvalues Amp-b, SLOPE, % MAP, % IPP, PI of the stored waveform, andsubsequently calculates one or more BP values, based on the calculatedone or more evaluated values Amp-b, SLOPE, % MAP, % IPP, PI and a cuffpressure value P_(c) at the time of supplying of the pulse waveform,according to the corresponding one or more of the relationships or mapsshown in FIGS. 41-45. The CPU 528 estimates a BP value of the subject,based on the thus calculated one or more BP values, according to aprescribed arithmetic expression.

As described above, the blood pressure BP employed as a parameter ineach of the relationships or maps of FIGS. 41-45 may be the systolic,mean, or diastolic BP value P_(sys), P_(mean), P_(dia) of the subject.For example, in the case where the maps of FIGS. 41-45 are determinedfor the systolic BP value P_(sys) of the subject, the CPU 528 estimates,at Step SA222, a systolic BP value of the subject according to thosemaps. This applies to the mean and diastolic BP values of the subject.Therefore, in the case where the maps of FIGS. 41-45 are determined foreach of the systolic, mean and diastolic BP values P_(sys), P_(mean),P_(dia) of the subject, the CPU 528 estimates, at Step SA222, asystolic, a mean and a diastolic BP value of the subject according tothose maps.

The CPU 528 determines, as an estimated BP value of the subject, anaverage of the calculated two or more BP values. Otherwise, the CPU 528may be modified to determine, as an estimated BP value, an average ofrespective weighted values of the calculated two or more BP values, oran average of one or more BP values obtained by removing the greatestand smallest values from the three or more calculated BP values.However, if the CPU 528 judges that the stored waveform is abnormal, theCPU 528 does not estimate a BP value of the subject. In this case,therefore, a negative judgment is made at the following Step SA223. TheCPU 528 judges whether the stored waveform is abnormal, by identifyingwhether each of one or more characteristic evaluated values Amp-b,SLOPE, % MAP, % IPP, PI of the waveform falls within a correspondingnormal range. In the case where the first pulse, i.e., first waveformobtained during the quick inflation of the cuff 510 is normal, the CPU528 estimates, at Step SA222, a BP value of the subject based on thefirst waveform. Accordingly, a positive judgment is made at Step SA223.

Steps SA222 is followed by Step SA223 to judge whether a BP estimationat Step SA222 has been completed. If a negative judgment is made at StepsA223, the control of the CPU 528 goes back to Step SA219 and thefollowing steps to quickly increase the cuff pressure P_(c). On theother hand, if a positive judgment is made, the control goes to StepSA224 to judge whether the estimated BP value of the subject isabnormal. For example, in the case of an estimated systolic BP value,the CPU 528 judges whether the estimated systolic BP value falls withina range of 100 to 200 mmHg; and in the case of an estimated diastolic BPvalue, the CPU 528 judges whether the estimated diastolic BP value fallswithin a range of 50 to 150 mmHg. If a negative judgment is made, theCPU 528 judges that the estimated BP value is abnormal.

If a positive judgment is made at Step SA224, i.e., if the estimated BPvalue is found to be abnormal, the control of the CPU 528 goes to StepSA225 to control the output device 538 to indicate that the estimated BPvalue is abnormally high or low. On the other hand, if a negativejudgment is made at Step SA224, the control goes to Step SA226 todetermine a modified target pressure, P_(CMR), such that the pressureP_(CMR) is equal to an estimated BP value of the subject. This estimatedsystolic BP value may be equal to the estimated systolic BP valueobtained at Step SA222, or a systolic BP value estimated based on themean or diastolic BP value obtained at Step SA222. Step SA226 isfollowed by Step SA227 to judge whether the cuff pressure P_(c) hasreached a pressure value, P_(CMR) +α, obtained by adding a prescribedbuffer or excess value to the pressure P_(CMR). If a negative judgmentis made at Step SA227, the control of the CPU 528 goes back to StepSA219 and the following steps to quickly increase the cuff pressureP_(c). On the other hand, if a positive judgment is made, the controlgoes to Step SA204 and the following steps to slowly decrease the cuffpressure P_(c) and carry out a BP measurement according to theoscillometric method.

As is apparent from the foregoing description, in the fifth embodiment,Step SA212 and a portion of the control device 526 for carrying out thisstep cooperate with each other to serve as means for determining therelationships shown in FIGS. 41-45, and Step SA222 and a portion of thecontrol device 526 for carrying out this step cooperate with each otherto serve as means for estimating a systolic, a mean or a diastolic BPvalue of the subject, based on (a) each characteristic evaluated valueof a pulse waveform supplied from the first band-pass filter 522 duringthe quick inflation of the cuff 510, and (b) a cuff pressure value P_(c)at the time of supplying of the pulse waveform, according to acorresponding one of the relationships or maps of FIGS. 41-45. Thesecond pulse wave signal SM2 supplied from the second band-pass filter523 may be used in place of the first pulse wave signal SM1, forsupplying a pulse waveform to the control device 526 or CPU 528.

The present BP measuring apparatus 600 estimates a BP value of thesubject, based on (a) a characteristic evaluated value of a pulsewaveform supplied during a quick cuff inflation period before a slowcuff deflation period, and (b) a cuff pressure value P_(c) at the timeof supplying of the pulse waveform. Thus, the apparatus 600 provides aconsiderably accurate estimated BP value of the subject shortly afterthe beginning of each of cyclic BP measurements carried out in theBP-monitor mode.

In the case where, at Step SA222, two or more BP values of the subjectare calculated according to the two or more relationships determined atStep SA212, the CPU 528 estimates a BP value of the subject based on thetwo or more calculated BP values. Therefore, the thus estimated BP valueof the subject enjoys a high accuracy.

Step SA226 and a portion of the control device 526 for carrying out thisstep cooperate with each other to serve as means for determining amodified target pressure P_(CMR) based on an estimated BP value of thesubject provided at Step SA222; and the pressure regulator valve 516 anda portion of the control device 526 for controlling the valve 516cooperate with each other to serve as means for regulating the cuffpressure P_(c) by quickly increasing the pressure P_(c) up to a pressurehigher by an access α than the determined target pressure P_(CMR) andthereafter slowly decreasing the pressure P_(c). Since the pressurehigher by the access α than the determined target pressure P_(CMR) is anecessary and adequate pressure higher than the estimated systolic BPvalue of the subject, the BP apparatus 600 effectively prevents the cuffpressure P_(c) from being increased up to an unnecessarily high value,thereby preventing the subject from feeling discomfort due to theunnecessarily high pressure.

Step SA224 and a portion of the control device 526 for carrying out thisstep cooperate with each other to serve as judging means for judgingwhether the blood pressure of the subject is abnormal, by comparing theestimated BP value of the subject obtained at Step SA222, with areference pressure range. The output device 538 and a portion of thecontrol device 526 for controlling the output device 538 cooperate witheach other to serve as means for outputting an indication that the bloodpressure of the subject is abnormal, when the judging means makes apositive judgment. Therefore, the present apparatus 600 ensures thatmedical workers can recognize a subject's blood pressure abnormality atan early point of time in a quick cuff inflation period. Accordingly,the medical workers such as doctors can take appropriate medical actionson the subject.

It is to be understood that the BP measuring apparatus 600 as the fifthembodiment may be modified in various ways.

For example, the BP apparatus 600 may be modified to operate accordingto the control program represented by the flow charts of FIGS. 46 and47. In this modified manner of operation, the pressure sensor 512 servesas a pressure detector which detects a cuff pressure P_(c), i.e.,pressing pressure of the cuff 510 wound around a body portion of aliving subject; the first or second band-pass filter 522, 523 serves asa pulse wave detector which detects, as a pulse wave, a pressureoscillation mixed with the cuff pressure P_(c) detected by the pressuresensor 512; the BP measuring device 508 determines a BP value of thesubject based on the change of successive pulse amplitudes producedduring the slow decreasing of the cuff pressure P_(c) ; the pressureregulator valve 516 and a portion of the control device 526 forcontrolling the valve 516 cooperate with each other to start a BPmeasurement by quickly increasing the cuff pressure P_(c) up to aprescribed target pressure value P_(CM) and subsequently slowlydecreasing the cuff pressure P_(c) and terminates the BP measurement bycompletely deflating the cuff 510 after the BP value of the subject hasbeen determined during the slow decreasing of the cuff pressure P_(c) bythe BP measuring device 508; a pulse amplitude/cuff pressure (PA/CP)memory area 680 of the RAM 630 stores each of the successive pulseamplitudes detected by the band-pass filter 522, 523 and a cuff pressurevalue P_(c) at the time of detection of each pulse amplitude, in theorder of detection of the pulse amplitudes. The control device 526 orCPU 528 determines an envelope representing a relationship between (a)the pulse amplitudes detected during the quick cuff inflation period bythe band-pass filter 522, 523 and (b) the cuff pressure values P_(c) atthe times of detection of those pulse amplitudes. In addition, the CPU528 operates for estimating a BP value of the subject, based on thedetermined envelope, according to a prescribed rule or relationship.

The control device 526 determines, in advance, a first envelope based on(a) a considerable great number of pulse amplitudes obtained by the BPmeasuring device 508 in measuring a BP value of the subject and (b) thecuff pressure values P_(c) when those pulse amplitudes are obtained.Since the first envelope is determined based on the many pulseamplitudes, the first envelope has a considerably high accuracy.Additionally, this envelope has a curved pattern proper to the subject.In a manner similar to that employed for determining the above envelope,the control device 526 determines a second envelope or curve connectinga considerable small number of pulse amplitudes obtained during a quickcuff inflation, over the respective cuff pressure values P_(c) whenthose pulse amplitudes are obtained. Based on the second envelope, theCPU 528 estimates a BP value of the subject. For example, like in theoscillometric BP measurement technique, a cuff pressure value P_(c)corresponding to a maximum value of the second envelope is estimated asa mean BP value of the subject; and two cuff pressure values P_(c)corresponding to two maximum slopes of the second envelope are estimatedas a systolic and a diastolic BP value of the subject (the higher cuffpressure P_(c) is estimated as the systolic BP value and the lower cuffpressure P_(c) is estimated as the diastolic BP value).

In this modified manner, the control device 526 or CPU 528 operates fordetermining, based on an estimated BP value of the subject, a modifiedtarget pressure P_(CMR) to which the cuff pressure P_(c) is quicklyincreased in a BP measurement. The CPU 528 controls the air pump 514 andthe pressure regulator valve 516 to slowly decrease the cuff pressureP_(c) after the pressure P_(c) has been raised up to the modified targetpressure P_(CMR). The CPU 528 also operates for identifying a subject'sblood pressure abnormality by comparing the estimated BP value with areference pressure value or range. If the subject's abnormal bloodpressure is identified, the CPU 528 controls the output device 538 toindicate that the blood pressure of the subject is abnormal.

Hereinafter, there will be described the operation of the BP apparatus600 as modified as described above, by reference to the flow charts ofFIGS. 46 and 47 employed in place of the flow charts of FIGS. 36 and 37.

Steps SB201 through SB205 are the same as Steps SA201 through SA205 ofFIG. 36, and are carried out to quickly increase the cuff pressureP_(c), subsequently slowly decrease the cuff pressure P_(c), and judgewhether one pulse has been supplied from the first band-pass filter 522.

At the following Step SB206, the CPU 528 stores, in the PA/CP memoryarea 680 of the RAM 630, the amplitude of one pulse supplied from thefirst band-pass filter 522 and the cuff pressure value Pc at the time ofsupplying of the one-pulse signal SM1. Step SB207 is the same as StepSA207 of FIG. 36, and is carried out to measure an actual BP value ofthe subject. Steps SB208 through SB210 are the same as Steps SA208through SA210 of FIG. 36, and are executed to judge whether the BPmeasurement has been completed, output the measured BP value or values,and reduce the cuff pressure P_(c) down to atmospheric pressure, therebyreleasing the subject's upper arm from the pressing of the cuff 510.

At the end of a BP measurement carried out at Steps SB201 through SB210,a considerably great number of pulse amplitudes and corresponding cuffpressure values P_(c) which are obtained in the BP measurement, arestored in the PA/CP memory area 680. Therefore, at the following StepSB211, the control device 526 or CPU 528 determines a first envelope,H₁, connecting data points representing the pulse amplitudes, PA, andthe corresponding cuff pressure values P_(c), as shown in FIG. 48. Sincethe first envelope H₁ is obtained based on the considerably great numberof data points obtained in the BP measurement, the first envelope H₁enjoys a considerably high accuracy, and represents a curved patternproper to the subject.

Step SB212 is the same as Step SA214 of FIG. 36. If a positive judgmentis made at Step SB212, the CPU 528 carries out Steps SB213 through SB217that are the same as Steps SA215 through SA219 of FIG. 37, therebyquickly increasing the cuff pressure P_(c). At the following Step SB220,the CPU 528 judges whether one pulse has been supplied from the firstband-pass filter 522 during the quick increasing of the cuff pressureP_(c), i.e., during the quick cuff inflation period. However, the CPU528 adopts, as a correct or true pulse, only a pulse which falls withina reference range, T (pulse period)±20%. The pulse period T is definedas the time distance between the respective upper (or lower) peaks ofthe last pair of successive two pulses each pulse of which has beenadopted as a true pulse. If the current pulse does not fall within thereference range, i.e., time window, the CPU 528 discards the pulse asnoise. If a positive judgment is made at Step SB211, the control of theCPU 528 goes to Step SB219 to store, in the PA/CP memory area 680, theamplitude of the pulse and the cuff pressure value P_(c) at the time ofsupplying of the pulse amplitude. Step SB219 is followed by Step SB220to determine, according to an envelope determination algorithm, a secondenvelope, H₂, representing a relationship between (a) the pulseamplitudes obtained during the quick cuff inflation period and (b) thecuff pressure values P_(c) when those pulse amplitudes are obtained.Since the number of the data points used to determine the secondenvelope H₂ is considerably small, the CPU 528 modifies the originalpolygonal line H₂ obtained by connecting the data points with oneanother, in such a manner that the modified curved line, i.e., secondenvelope H₂ is similar to the pattern of the first envelope H₁. FIGS.49(A), 49(B), 49(C), and 49(D) shows examples of the second envelope H₂which can be obtained at Step SB220.

At the following Step SB221, the CPU 528 estimates a BP value of thesubject based on the second envelope H₂ which is determined at StepSB220 based on the pulses obtained during the quick cuff inflationperiod. Specifically described, like the oscillometric BP determinationtechnique, a cuff pressure value corresponding to the maximum value ofthe second envelope H₂ is determined as an estimated mean BP value ofthe subject, and two cuff pressure values corresponding to two maximumslopes of the second envelope H₂ are determined as an estimated systolicand an estimated diastolic BP value of the subject (the higher cuffpressure is determined as the estimated systolic BP value and the lowercuff pressure is determined as the estimated diastolic BP value).

Step SB221 is followed by Step SB222 to judge whether the BP estimationat Step SB221 has been completed. If a negative judgment is made at StepSB222, the control of the CPU 528 goes back to Step SB217 and thefollowing steps to read in subsequent pulses. On the other hand, if apositive judgment is made, the control goes to Steps SB223 through SB226that are the same as Steps SA224 through SA227. If at Step SB523 the CPU528 judges that the estimated BP value of the subject determined at StepSB221 is abnormal, the CPU 528 controls, at Step SB224, the outputdevice 538 to indicate that the estimated BP value of the subject isabnormal. On the other hand, if at Step SB523 the CPU 528 does not judgethat the estimated BP value of the subject determined at Step SB221 isabnormal, the CPU 528 determines, at Step SB225, a modified targetpressure P_(CMR). If the actual cuff pressure P_(c) reaches a pressurehigher by an excess or buffer value α than the modified target pressureP_(CMR), the control of the CPU 528 goes back to Step SB204 and thefollowing steps.

In the modified BP monitor operation in accordance with the flow chartsof FIGS. 46 and 47, the first band-pass filter 522 serves as a pulsedetector which detects pulse amplitudes while the cuff pressure P_(c) isquickly increased. Step SB220 and a portion of the control device 526for carrying out this step cooperate with each other to serve as meansfor determining a second envelope H₂ representing a relationship between(a) the respective amplitudes of the pulses detected by the pulsedetector during the quick cuff inflation period and (b) the respectivecuff pressure values at the times of detection of those pulseamplitudes. Step SB221 and a portion of the control device 526 forcarrying out this step cooperate with each other to serve as means forestimating a BP value of the subject, based on the second envelope H₂determined at Step SB220, according to a prescribed BP estimation rulesuch as a known oscillometric BP determination rule. Thus, the apparatus600 modified as described above provides a considerably accurateestimated BP value of the subject based on the second envelope H₂obtained in each quick cuff inflation period before each slow cuffdeflation period, i.e., shortly after the beginning of each cyclic BPmeasurement carried out in the BP-monitor mode. Thus, medical workerscan quickly know the considerably accurate BP value or values of thesubject.

In addition, since at Step SB218 the CPU 528 adopts only pulses each ofwhich falls inside an appropriate time window, i.e., discards "noise"pulses which do not fall inside the time window, the estimated BP valuesof the subject enjoy a high reliability.

Step SB225 and a portion of the control device 526 for carrying out thisstep cooperate with each other to serve as means for determining amodified target pressure P_(CMR) based on an estimated BP value of thesubject provided at Step SB221; and the pressure regulator valve 516 anda portion of the control device 526 for controlling the valve 516cooperate with each other to serve as means for regulating the cuffpressure P_(c) by quickly increasing the pressure P_(c) up to a pressurehigher by the access a than the determined target pressure P_(CMR) andthen slowly decreasing the pressure P_(c). Since the pressure higher bythe access a than the modified target pressure P_(CMR) is a necessaryand adequate pressure higher than an estimated systolic BP value of thesubject, the BP apparatus 600 effectively prevents the cuff pressureP_(c) from being increased up to an unnecessarily high value, therebypreventing the subject from feeling discomfort due to the unnecessarilyhigh pressure.

Step SB223 and a portion of the control device 526 for carrying out thisstep cooperate with each other to serve as judging means for judgingwhether the blood pressure of the subject is abnormal, by comparing theestimated BP value of the subject obtained at Step SB221, with areference pressure value or range. The output device 538 and a portionof the control device 526 for controlling the output device 538cooperate with each other to serve as means for outputting an indicationthat the blood pressure of the subject is abnormal, when the judgingmeans makes a positive judgment. Therefore, the present apparatus 600 asmodified also ensures that medical workers can recognize a subject'sblood pressure abnormality at an early point of time in a quick cuffinflation period. Accordingly, the medical workers such as doctors cantake appropriate medical actions on the subject.

While in the BP monitor operation in accordance with the flow charts ofFIGS. 36 and 37 the relationships determined at Step SA212 once in thefirst BP monitor cycle following each BP measurement are used toestimate a BP value of the subject also in each of the subsequent BPmonitor cycles, without being updated, it is possible to modify the BPapparatus 600 to carry out BP measurements at regular intervals of timeand periodically determine new relationships based on the BP value orvalues determined in each BP measurement.

Although the cuff pressure P_(c) is monotonously increased during eachquick cuff inflation period and pulse amplitudes are obtained in theprocess in which the cuff pressure P_(c) is increased in that manner, itis possible to stepwise increase the cuff pressure Pc while holding thepressure P_(c) at pressure steps each for a prescribed short duration,so that the control device 526 obtains one or more pulses when thepressure P_(c) is held at each step. In the latter case, the controldevice 526 can utilize pulses having more accurate waveforms.

While at Step SB221 of the flow chart of FIG. 47 the oscillometric BPdetermination technique is utilized to estimate a BP value of thesubject based on the second envelope H₂, it is possible to employ otherBP estimation methods or techniques. For example, it is possible toemploy an easier technique to determine, as an estimated systolic, mean,or diastolic blood pressure of the subject, a cuff pressure value P_(c)corresponding to a point of intersection of the second envelope H₂ and abroken line corresponding to a prescribed pulse amplitude, as shown inFIG. 49(A).

Referring next to FIG. 50, there is shown an automatic blood pressure(BP) measuring apparatus 700 as a sixth embodiment of the presentinvention.

In FIG. 50, reference numeral 710 designates an inflatable cuff adaptedto be wound around an upper arm of a living subject (e.g., patient) soas to press the upper arm. The cuff 710 includes an inflatable bag (notshown). The inflatable bag of the cuff 510 is connected via piping 720to a pressure sensor 712, a quick deflation valve 714, a slow deflationvalve 716, and an air pump 718.

The pressure sensor 712 detects an air pressure in the cuff 710 ("cuffpressure") and supplies a detection signal, SP, to a cuff-pressuredetector circuit 722 and a pulse-wave detector circuit 724. Thecuff-pressure detector circuit 722 includes a low-pass filter (notshown) which permits only a static-pressure component of the detectionsignal SP to pass therethrough, thereby supplying a cuff-pressuresignal, SK, representing the detected static cuff pressure, P_(c), to acontrol circuit 728 via an analog-to-digital (A/D) converter 726. Thepulse-wave detector circuit 724 includes a band-pass filter (not shown)which permits only an oscillation component of the detection signal SPto pass therethrough, thereby supplying a pulse-wave signal, SM,representing a pulse wave of the subject, to the control circuit 728 viathe A/D converter 726. The pulse wave is generated in the cuff 710because of the pulsation of arteries of the upper arm under the cuff 710in synchronism with the heartbeats of the subject, while the cuffpressure P_(c) changes within an appropriate pressure range. Thus, thepulse wave generated in the cuff 710 is obtained as the oscillationcomponent of the detection signal SP supplied from the pressure sensor712.

The control circuit 728 is essentially constituted by a microcomputerincluding a CPU 730, a ROM 732, a RAM 734, and an output interface 736.The CPU 730 receives the digital signals SK and SM from the A/Dconverter 726, and processes those signals by utilizing thetemporary-storage function of the RAM 734 and the control programs oralgorithms pre-stored in the ROM 732. The CPU 730 supplies drive signalsto the quick deflation valve 714, slow deflation valve 716, and air pump718, to measure a blood pressure (BP) value of the subject. The CPU 730carries out the pre-stored algorithms to supply, to an output device738, a BP signal representing the measured BP value, ameasurement-condition signal indicating whether the condition ofmeasurement of the BP value is sufficiently proper, and apulse-amplitude signal representing respective amplitudes of a series ofsuccessive pulses of the pulse wave (i.e., pulse-wave signal SM). Theoutput device 738 includes an image display panel (not shown; e.g.,liquid-crystal display panel) which has a matrix of picture elements.The output device 538 may further include a printer, as needed, whichrecords using an ink an image on a recording sheet. The output device738 outputs, on the image display panel or the recording sheet, the BPvalue of the subject, the propriety or non-propriety of the condition ofthe BP measurement, and the series of pulse amplitudes. Referencenumeral 740 designates a START/STOP button manually operable foralternately starting and stopping the operation of the present BPmeasuring apparatus 700.

Hereinafter, there will be described the automatic BP measuringoperation of the BP apparatus 700 constructed as described above, byreference to the flow charts of FIGS. 51 and 52.

Initially, at Step S301, the CPU 730 judges whether the START/STOPbutton 740 has been operated for starting the operation of the presentapparatus 700, based on a START or STOP signal supplied from the button740. If a negative judgment is made at Step S301, the control of the CPU730 waits for receiving the START signal from the button 740. Meanwhile,if a positive judgment is made, the control of the CPU 730 proceeds withStep S302 to close the quick and slow deflation valves 714, 716 anddrive the air pump 718 so as to start supplying a pressurized air to theinflatable cuff 710 and thereby increasing the air pressure in the cuff510, i.e., cuff pressure P_(c).

Step S302 is followed by Step S303 to judge whether the cuff pressureP_(c) has been increased up to a prescribed target pressure, P_(m)(e.g., 180 mmHg), which is sufficiently higher than a systolic bloodpressure of the subject. If a negative judgment is made at Step S303,the CPU 730 repeats Step S303 to continue to increase the cuff pressureP_(c). Meanwhile, if a positive judgment is made at Step S301, thecontrol of the CPU 730 proceeds with Step S304 to stop the air pump 718and open the slow deflation valve 716 so as to start deflating the cuff710, i.e., decreasing the cuff pressure P_(c). This cuff deflation orpressure decreasing is carried out slowly at a rate of, e.g., 2 to 3mmHg/sec suitable for BP measurements. During this slow cuff deflation,Steps S305 and S306 are repeatedly carried out for determining a BPvalue of the subject.

At Step S305, the BP determination subroutine represented by the flowchart of FIG. 52 is repeated at a short cycle or period, e.g., everyfour milliseconds. In this subroutine, respective amplitudes, R, of aseries of successive pulses of the pulse wave signal SM are determinedand pre-treated, and a BP value or values of the subject is or aredetermined based on the pulse amplitudes R according to a known BPdetermination algorithm.

First, at Step ST1, the CPU 730 reads, at a sampling period, respectivemagnitudes of the pulse wave signal SM supplied thereto from the A/Dconverter 726, and judges whether the CPU 730 has received a length ofthe pulse wave signal SM corresponding to one pulse having an amplitude,i.e., one cycle of heartbeat of the subject. If a negative judgment ismade at Step ST1, the CPU 730 repeats Step ST1. Meanwhile, if a positivejudgment is made at Step ST1, that is, if the CPU 730 reads in an upperpeak and a lower peak of one pulse, the control of the CPU 730 proceedswith Step ST2 to calculate an amplitude, R_(i), of the pulse bysubtracting the lower-peak magnitude thereof from the upper-peakmagnitude thereof. Step ST2 is followed by Step ST3 to judge whether thecalculated pulse amplitude R_(i) is abnormal, by identifying such achange of the current amplitude R_(i) from the preceding amplitudeR_(i-1) which cannot physiologically be expected to occur. For example,in the case where the current amplitude R_(i) is obtained before thecuff pressure P_(c) is decreased below a mean BP value of the subject,the CPU 730 makes a positive or "abnormality" judgment if the currentamplitude R_(i) is smaller than half the preceding amplitude R_(i-1) orgreater than four times the same R_(i-1) ; and, in the case where thecurrent amplitude R_(i) is obtained after the cuff pressure P_(c) isdecreased below the mean BP value of the subject, the CPU 730 makes an"abnormality" judgment if the current amplitude R_(i) is smaller thanhalf the preceding amplitude R_(i-1) or greater than one and a halftimes the same R_(i-1).

If a positive judgment is made at Step ST3, the control of the CPU 730goes back to Step ST1 and the following steps. On the other hand, if anegative judgment is made at Step ST3, the control goes to Step ST4 tostore, in an appropriate memory area of the RAM 734, the current pulseamplitude R_(i) and a cuff pressure value P_(c) at the time of supplyingof the pulse amplitude R_(i). Step ST4 is followed by Step ST5 to judgewhether the current amplitude R_(i) is the first normal amplitudefollowing the last abnormal amplitude. If a negative judgment is made atStep ST5, the control of the CPU 730 bypasses Step ST6 and goes to StepST7. On the other hand, if a positive judgment is made at Step ST5, thecontrol goes to Step ST6 to carry out the "amp-filter" treatment that isdisclosed in, e.g., the aforementioned non-examined Japanese patentapplication laid open under Publication No. 63-51837. That is, one ormore abnormal amplitudes R_(i-k), . . . , R_(i-2), R_(i-1) preceding thecurrent normal amplitude R_(i) is or are subjected to linearinterpolation based on the current amplitude R_(i) and the normalamplitude R_(i-k-1) preceding the one or more abnormal amplitudesR_(i-k), . . . , R_(i-2), R_(i-1).

At the following Steps ST7 and ST8, the series of pulse amplitudes R_(n)that have been subjected to the amp-filter treatment at Step ST6, asneeded, are subjected to the "median-filter" treatment so as to smoothenthe amplitudes R_(n). The median-filter treatment is disclosed in, e.g.,the above Japanese patent application. Specifically, at Step ST7, theCPU 730 selects an odd number (e.g., five) of successive pulseamplitudes R_(i-4), R_(i-3), R_(i-2), R_(i-1), R_(i) including thecurrent amplitude R_(i). Step ST7 is followed by Step ST8 to replace themiddle amplitude R_(i-2) by the third greatest amplitude R_(j) of allthe five amplitudes. In the present embodiment, Steps ST5 to ST8 and aportion of the control circuit 728 for carrying out those stepscooperate with each other to serve as means for smoothening the detectedpulse amplitudes R_(n). At Step ST7, the CPU 730 may be programmed toselect three or seven or other odd number of successive pulse amplitudesother than five successive amplitudes.

After at Step ST8 the series of pulse amplitudes R_(n) are smoothened,the control of the CPU 730 proceeds with Step ST9, i.e., BPdetermination algorithm for determining a systolic and a diastolic BPvalue of the subject based on the thus smoothened pulse amplitudes,S_(n). Specifically described, the respective cuff pressure values P_(c)corresponding to the two pulse amplitudes S_(i) at which the series ofpulse amplitudes S_(n) significantly greatly change, are selected, andthe selected two pressure values P_(c) are determined as the systolicand diastolic BP values of the subject. The two determined BP values maybe corrected, as needed, based on a prescribed relationship betweensystolic and diastolic BP values and/or a prescribed relationshipbetween systolic or diastolic BP value and mean BP value. The twodetermined BP values are stored in an appropriate memory area of the RAM734. Thus, in the present embodiment, the BP values of the subject aredetermined based on a pulse wave in the form of a heartbeat-synchronoussignal wave, i.e., a pressure oscillation produced in the cuff 710 insynchronism with the heartbeats of the subject, the cuff 710 being woundaround a body portion of the subject to press the body portion.

Back to the flow chart of FIG. 51, the control of the CPU 730subsequently goes to Step S306 to judge whether the BP determinationsubroutine at Step S305 has been completed. For a while shortly afterthe beginning of the slow decreasing of the cuff pressure P_(c), asufficient number of pulse amplitudes S_(n) have not been obtained.Therefore, the CPU 730 repeats Steps S305 and S306. Meanwhile, if apositive judgment is made at Step S306, that is, if the BP values of thesubject have been determined at Step ST9 of FIG. 52, the control of theCPU 730 goes to Step S307.

At Step S307, the CPU 730 opens the quick deflation valve 715 tocompletely deflate the cuff 710, i.e., reduce the cuff pressure P_(c)down to atmospheric pressure. At the following Steps S308, S309, andS310, the CPU 730 calculates a correction degree, C, i.e., degree ofcorrection of the series of smoothened pulse amplitudes S_(n) from theseries of detected pulse amplitudes R_(n). More specifically, at StepS308, the CPU 730 calculates a sum, SD, of respective absolute values,|S_(i) -R_(i) |, each of which is obtained as a difference of pulseamplitudes R_(i) and S_(i) which correspond to a cuff pressure valueP_(c) within a prescribed pressure range, according to the followingexpression (3):

    SD=Σ|S.sub.i -R.sub.i |            (3)

The above-mentioned pressure range may be pre-determined to cover thepulse amplitudes R_(i), S_(i) ranging from the pulse amplitude R_(u-1),S_(u-1) outside and adjacent the pulse amplitude R_(u), S_(u)corresponding to the systolic BP value of the subject determined at StepST9, to the pulse amplitude R_(t+1), S_(t+1) outside and adjacent thepulse amplitude R_(t), S_(t) corresponding to the determined diastolicBP value of the subject.

At the following Step S309, the CPU 730 calculates a sum, SS, ofrespective smoothened pulse amplitudes S_(i) which correspond to thecuff pressure values P_(c) within the above-mentioned pressure range,according to the following expression (4):

    SD=ΣS.sub.i                                          (4)

Step S309 is followed by Step S310 to calculate, as the correctiondegree C, a percentage of the sum SD to the sum SS, according to thefollowing expression (5):

    C=(SD/SS)×100 (%)                                    (5)

Thus, in the present embodiment, Steps S308 to S310 and a portion of thecontrol circuit 728 for carrying out those steps cooperate with eachother to serve as means for calculating the correction degree C.

In FIG. 53, the first sum SD corresponds to a first area as a sum ofshadowed areas, A; the second sum SS corresponds to a second areabounded by a polygonal line representing the series of smoothened pulseamplitudes S_(i) and a base line parallel to the axis of abscissa, i.e.,axis indicative of cuff pressure P_(c). Therefore, the correction degreeC corresponds to a ratio of the first area to the second area.

Step S310 is followed by Step S311 to control the output device 738and/or another output device (not shown) to output the systolic anddiastolic BP values, and pulse rate, of the subject. The pulse rate isdetermined based on the difference between the times of detection ofrespective upper (or lower) peaks of two successive pulses. In addition,at Step S311, the CPU 730 controls the output device 738 to record, on arecording sheet 742 shown in FIG. 53, a first graphic representation 744including the first series of detected pulse amplitudes R and the secondseries of smoothened pulse amplitudes S, superimposed on each other, ina two-dimensional coordinate system defined by a first axis indicativeof cuff pressure P_(c) and a second axis indicative of pulse amplitudesR, S. The output device 738 also records, on the sheet 742, a secondgraphic representation 746 in a side-by-side relation with the firstgraph 744. The second graph 746 is indicative of a propriety ofmeasurement condition, i.e., a correction degree C. The length of the"black" horizontal bar 746 corresponds to the determined correctiondegree C. The longer the bar 746 is, the higher the correction degree Cis. The higher correction degree C indicates the higher degree of mixingof "noise" pulses with true pulses. In the first graph 744, the firstseries of detected pulse amplitudes R are indicated at vertical lines,and the second series of smoothened pulse amplitudes S are indicated ata polygonal line. The shadowed areas A bounded by (a) the envelope ofthe vertical lines and (b) the polygonal line represents the first sumSD. The two cuff pressure values P_(c) corresponding to the systolic anddiastolic BP values of the subject determined at Step ST9, are indicatedat symbols ▴ and Δ, respectively, recorded along the first axis. Thesecond graph 746 includes three marks "L", "N", and "H" indicating alow, a normal, and a high correction degree C, i.e., three degrees ofmixing of "noise" pulses with true pulses, respectively. Thus, thesecond graph 746 indicates the degree of propriety of the currentmeasurement condition under which the current BP values of the subjecthave been measured. Medical workers can recognize the currentmeasurement condition by comparing the length of the "black" horizontalbar C with the marks "L", "N" or "H". For example, the normal correctiondegree C corresponding to the mark "N" may be selected at 5%, and thehigh correction degree C corresponding to the mark "H" may be selectedat 9%. In the present embodiment, the control circuit 728 serves as acontrol device which controls the output device 738.

As is apparent from the foregoing description, the BP measuringapparatus 700 operates in such a way that at Step S311 the output device738 outputs the first series of detected or sampled pulse amplitudes Rand the second series of smoothened or processed pulse amplitudes S, thetwo sorts of pulse amplitudes R, S being superimposed on each other inthe common two-dimensional graph 744. Therefore, medical workers such asdoctors can visually recognize the differences, D_(i), of the detectedpulse amplitudes R_(i) and the corresponding smoothened pulse amplitudesS_(i). The differences D_(i) correspond to the sum of areas A shown inFIG. 53. The differences D_(i) may be increased due to external causessuch as the physical motion of the subject or noise due to peripheraldevices. Medical workers can easily judge whether the measured BP valuesof the subject contain excessively large errors due to the externalcauses, by recognizing the respective positions of the differencesD_(i), i.e., areas A with respect to the first axis, i.e., cuff-pressureaxis of the common two-dimensional graph 744. That is, the medicalworkers can easily identify whether the condition of the BP measurementis proper. For example, in the case where the sum SD of the differencesD_(i) is excessively large because the series of smoothened pulseamplitudes S have been excessively largely corrected particularly in arange of cuff pressure P_(c) between the determined systolic anddiastolic BP values of the subject indicated at the respective symbols▴, Δ in the graph 744, medical workers can easily judge that the seriesof detected pulse amplitudes R have been excessively largely influencedby external causes and that the accuracy of measured BP values of thesubject is insufficiently low and the condition of the BP measurement isnot appropriate.

Since in the present embodiment the first series of detected pulseamplitudes R are indicated by vertical lines, the second series ofsmoothened pulse amplitudes S are indicated by a polygonal line, and thedifferences D of the two sorts of pulse amplitudes R, S are indicated bythe shadowed areas A bounded by (a) the envelope of the vertical linesand (b) the polygonal line, observers can easily recognize the magnitudeor amount of the sum of differences D, i.e., first sum SD.

In the present embodiment, the control circuit 728 or CPU 730 calculatesthe correction degree C as the percentage of the sum of areas A to thearea bounded by (a) the polygonal line of the smoothened pulseamplitudes S and (b) the base line. The correction degree C indicatesthe degree of correction of the smoothened pulse amplitudes S from thedetected pulse amplitudes R. The correction degree C is indicated by thehorizontal bar in the second graph 746 provided in a side-by-siderelation with the first graph 744 on the recording sheet 742 or on theimage display panel (not shown) of the output device 738. Thus,observers can visually know what percent of correction has been made onthe detected pulse amplitudes R. The observers can judge, based on thecorrection degree C, whether the measured BP values of the subjectcontain excessively large errors due to external factors, i.e., whetherthe condition of the BP measurement is proper. In addition, the secondgraph 746 includes the three marks or indicias "L" (i.e., `noise islow`), "N" (`noise is normal`) and "H" (`noise is high`) respectivelyindicating the three degrees of propriety of the measurement condition.Thus, operators who are not familiar with the BP apparatus 700 caneasily judge, based on the horizontal bar and the marks of the secondgraph 746, whether the measurement condition is proper or appropriate.For example, in the case where the right-hand end of the horizontal barindicative of the correction degree C reaches a position between themarks "L" and "N", that is, a position where the correction degree C issmaller than 5%, the operators can judge that the condition of the BPmeasurement is proper. In the present embodiment, the correction degreeC indicates the degree of propriety of the measurement condition, andthe horizontal bar representing the correction degree C is output in aside-by-side relation with the marks "L", "N", "H" each representing adegree of propriety of measurement condition.

FIGS. 54, 55, 56, and 57 shows other forms of expression eachcorresponding to the two-dimensional graph 744 shown in FIG. 53. In FIG.54, the series of smoothened pulse amplitudes S are indicated in thesame manner as that employed in FIG. 53, but the series of detectedpulse amplitudes R are indicated by not vertical lines but a polygonalline, like the smoothened pulse amplitudes S. In addition, areas Abounded by those two polygonal lines are not shadowed. Also in thiscase, observers can clearly recognize the differences D_(i) of the twosorts of pulse amplitudes R, S in the common two-dimensional graph, andcan easily judge whether the measured BP values of the subject containexcessively large errors due to external factors, i.e., whether themeasurement condition is proper, based on (a) the sum of differencesD_(i) and (b) the respective positions of the differences D_(i) withrespect to the first axis of the common two-dimensional graph.

In the two-dimensional graph shown in FIG. 54, a portion or portions ofthe polygonal line of the smoothened pulse amplitudes S which is or areseparate from a corresponding portion or portions of the polygonal lineof the detected pulse amplitudes R, indicate(s) that data correction hasbeen carried out on the portion or portions. Therefore, observes caneasily recognize the differences D_(i) of the two sorts of pulseamplitudes R, S.

In the two-dimensional graph shown in FIG. 55, both the two sorts ofpulse amplitudes R, S are indicated at bars, and areas A correspondingto the differences D_(i) of the two sorts of pulse amplitudes R, S areindicated in a color or pattern different from a color or pattern usedto indicate the other portions of the bars. For example, a light and adark color may be used to distinguish the areas A and the other portionsfrom each other. In this case, too, observers can clearly recognize thedifferences D_(i) of the two sorts of pulse amplitudes R, S in thecommon two-dimensional graph, and can easily judge whether the measuredBP values of the subject contain excessively large errors due toexternal factors, i.e., whether the measurement condition is proper,based on (a) the sum of differences D_(i) and (b) the respectivepositions of the differences D_(i) with respect to the first axis of thecommon two-dimensional graph.

In the two-dimensional graph shown in FIG. 56, one of the two sorts ofpulse amplitudes R, S (the smoothened pulse amplitudes S in the figure)are indicated at a polygonal line and the other (the detected pulseamplitudes R in the figure) are indicated at vertical bars. In thiscase, observers can visually recognize (a) a vertical bar or bars higherthan a corresponding portion or portions of the polygonal line, (b) aportion or portions of the polygonal line higher than a correspondingvertical bar or bars, and (c) the differences D_(i) of the heights ofthe higher bars and the heights of the corresponding portions of thepolygonal line and the differences D_(i) of the heights of the higherportions of the polygonal line and the heights of the correspondingbars. Thus, the observers can clearly recognize the differences D_(i) ofthe two sorts of pulse amplitudes R, S in the common two-dimensionalgraph, and can easily judge whether the measured BP values of thesubject contain excessively large errors due to external factors, i.e.,whether the measurement condition is proper, based on (a) the sum ofdifferences D_(i) and (b) the respective positions of the differencesD_(i) with respect to the first axis of the common two-dimensionalgraph.

In the two-dimensional graph shown in FIG. 57, one of the two sorts ofpulse amplitudes R, S are indicated at vertical lines and the other areindicated at a polygonal line, like in the graph shown in FIG. 53.However, the differences D_(i) of the two sorts of pulse amplitudes R, Sare not indicated at shadowed areas A, unlike the graph of FIG. 53. Inthis case, however, observers can visually recognize (a) a vertical lineor lines higher than a corresponding portion or portions of thepolygonal line, (b) a portion or portions of the polygonal line higherthan a corresponding vertical line or lines, and (c) the differencesD_(i) of the heights of the higher vertical lines and the heights of thecorresponding portions of the polygonal line and the differences D_(i)of the heights of the higher portions of the polygonal line and theheights of the corresponding vertical lines. Thus, the observers canclearly recognize the differences D_(i) of the two sorts of pulseamplitudes R, S in the common two-dimensional graph, and can easilyjudge whether the measured BP values of the subject contain excessivelylarge errors due to external factors, i.e., whether the measurementcondition is proper, based on (a) the sum of differences D_(i) and (b)the respective positions of the differences D_(i) with respect to thefirst axis of the common two-dimensional graph.

In each of the two-dimensional graphs shown in FIGS. 54-57, the measuredsystolic and diastolic BP values of the subject are indicated at symbols▴, Δ provided along the first axis, i.e., cuff-pressure axis of eachtwo-dimensional graph. Therefore, observers can easily specify, in thetwo-dimensional graph, a cuff-pressure range to be utilized in judgingwhether the measurement condition is proper (e.g., cuff-pressure rangebetween the measured systolic and diastolic BP values).

A horizontal bar representing a determined correction degree C may beindicated together with each of the graphs shown in FIGS. 54-57, likethe second graph 746 indicated with the first graph 744 shown in FIG.53. Alternatively, each of the graphs of FIGS. 54-57 may not beaccompanied by a horizontal bar representing a correction degree C.Otherwise, the BP measuring apparatus 700 may be provided with anotheroutput device which indicates the correction degree C, i.e., degree ofpropriety of the measurement condition.

The output device 738 may be modified to output a correction degree C indigits in a measurement-condition indication area 846 provided on arecording sheet 842 shown in FIG. 58. A pulse-amplitude indication arealike the first graph 744 shown in FIG. 53 is not provided on therecording sheet 842. Below the correction degree C indicated in a digitor digits, notes are provided which read as follows: "3>C: NOISE ISLOW", "6>C≦3: NOISE IS NORMAL", and "C≦6: NOISE IS HIGH (ANOTHERMEASUREMENT IS NECESSARY)". Those notes may be used as standards injudging whether the correction degree C is excessively high. In thiscase, too, observers can easily judge whether the measured BP values ofthe subject contain excessively large errors due to external factors,i.e., whether the measurement conditions is proper, based on the outputdata 846 recorded on the sheet 842.

The indication of the degree of propriety of the measurement conditionmay otherwise be made than shown in FIG. 58 where the correction degreeC in digits is recorded on the sheet 842. For example, the BP apparatus700 may be modified to select one of evaluation messages, such as "NOISEIS LOW" or "NOISE IS HIGH", which corresponds to the determinedcorrection degree C, and output the selected message in themeasurement-condition indication area 846 of the recording sheet 842. Inthe latter case, as shown in FIG. 59, Steps S312, S313a, S313b, andS313c are provided after Step S310 of the flow chart of FIG. 51. Morespecifically, at Step S312, the CPU 730 compares the determinedcorrection degree C with two reference values respectively correspondingto the evaluations of "NOISE IS NORMAL" and "NOISE IS HIGH", and judgeswhether the determined correction degree C is smaller than 3 as thefirst reference value, whether the degree C is not smaller than 3 andsmaller than 6 as the second reference value, or whether the degree C isnot smaller than 6. In the case of C<3, the control of the CPU 730 goesto Step S313a to select an evaluation message "NOISE IS LOW" and storethe message in a memory area, M, of the RAM 734; in the case of 6>C≦3,the control goes to Step S313b to select an evaluation message "NOISE ISNORMAL" and store the message in the memory M; and, in the case of C≦6,the control goes to Step S313c to select an evaluation message "NOISE ISHIGH" and store the message in the memory M. Following Step S313a,S313b, or S313c, the control of the CPU 730 goes to Step S314 providedin place of Step S311 of FIG. 51. At Step S314, the CPU 730 controls theoutput device 738 to output, in place of the correction degree C, theevaluation message selected at Step S313a, S313b, or S313c, in themeasurement-condition indication area 846 of the recording sheet 842.Otherwise, the BP apparatus 700 may be provided with a plurality oflamps related with different correction degrees C, so that the BPapparatus 700 may light one of the lamps which corresponds to adetermined correction degree C.

It is to be understood that the sixth embodiment may be modified inother manners.

For example, while the BP apparatus 700 measures the BP values of thesubject by utilizing, as a heartbeat-synchronous signal wave, a pulsewave produced in the cuff 710, it is possible to provide a microphone inthe cuff 710 and detect using the microphone the Korotkoff sounds thatare arterial sounds produced from the arteries of a body portion beingpressed by the cuff 710. In the latter case, the Korotkoff sounds areutilized as a heartbeat-synchronous signal wave in BP measurements.

In the sixth embodiment, Step ST3 and a portion of the control circuit728 for carrying out this step cooperate with each other to serve asmeans for judging whether each detected or determined pulse amplitudeR_(i) falls within a reference range and, if the pulse amplitude R_(i)does not fall within the reference range, judging that the pulseamplitude R_(i) is abnormal. Steps ST5 and ST6 and a portion of thecontrol circuit 728 for carrying out these steps cooperate with eachother to serve as means for replacing an abnormal pulse amplitude oramplitudes R_(i) with a value or values obtained by interpolating twonormal pulse amplitudes R_(i) sandwiching the abnormal amplitude oramplitudes R_(i). Step ST7 and a portion of the control circuit 728 forcarrying out this step cooperate with each other to serve as means forsequentially selecting an odd number of successive pulse amplitudesR_(i-2), R_(i-1), R_(i), R_(i+1), R_(i+2) from the series of determinedpulse amplitudes R. Step ST8 and a portion of the control circuit 728for carrying out this step cooperate with each other to serve as meansfor replacing the middle or center pulse amplitude R_(i) with the pulseamplitude R_(j) which has a median amplitude of the selected odd numberof pulse amplitudes. Steps ST3, ST5, ST6, ST7, and ST8 and a portion ofthe control circuit 728 for carrying out these steps cooperate with eachother to serve as means for smoothening the series of determined pulseamplitudes R. However, other kinds of smoothening means may be employed.

For example, Steps ST3, ST5, and ST6 may be omitted from the flow chartof FIG. 52, or Steps ST7 and ST8 may be omitted from the same.Alternatively, Step ST8 may be replaced with a step where the middlepulse amplitude R_(i) is replaced with an average of the selected oddnumber of pulse amplitudes R_(i-2), R_(i-1), R_(i), R_(i+1), R_(i+2).Only if a smoothing technique in any sense is applied to a series ofdetermined pulse amplitudes R in determining a BP value of a livingsubject, the BP apparatus 700 outputs the first series of determinedpulse amplitudes R and the second series of smoothened pulse amplitudesS, such that one series of the first and second series of pulseamplitudes R, S are superimposed on the other series in a commontwo-dimensional graph. In addition, the BP apparatus 700 outputs, basedon a determined correction degree C, a degree of propriety of themeasurement conditions under which the BP value of the subject isobtained. Thus, in any case, medical workers can easily judge, from theoutput of the BP apparatus 700, whether the measurement condition isproper or appropriate.

In each of the graphs shown in FIGS. 53 to 57, it is possible toexchange two symbols with each other for representing the two series ofpulse amplitudes R, S, respectively. Moreover, in place of the verticallines or the vertical bars, it is possible to use other symbols,patterns, or figures such as "star" mark or "snow" mark. In the graph ofFIG. 53, the areas A may not be blacked out and only the polygonal line,vertical lines, and envelope of the vertical lines may be presented. Inthe graph of FIG. 54, the areas A may be blacked out. In each graph, theareas A may otherwise be made distinct by, e.g., being hatched with,e.g., oblique lines or a checked pattern.

Although in each of the graphs shown in FIGS. 53 and 55 the areas A areblacked out in the same manner irrespective of whether the determinedpulse amplitudes R are higher or lower than the corresponding smoothenedpulse amplitudes S, it is possible to distinguish some of the areas Awhere the determined pulse amplitudes R are higher than thecorresponding smoothened pulse amplitudes S, from the other of the areasA where vice versa, by using different hatchings such as differentoblique-line patterns.

From the output 742 of the BP apparatus 700 shown in FIG. 53, it ispossible omit either one of (a) the pulse-amplitude indication area 744where the two series of pulse amplitudes R, S are output, and (b) themeasurement-condition indication area 746 where the correction degree Cis output. From either one of the two sorts of information 744, 746provided by the apparatus 700, medical workers can easily judge whetherthe measured BP values of the living subject contain excessively largeerrors due to external factors, i.e. , whether the measurement conditionis proper. In the case where the correction degree C is not determinedor output, Steps S308 to S310 of the flow chart of FIG. 51 are omitted.

Although in the sixth embodiment the correction degree C is determinedbased on a ratio of the sum SD to the sum SS of the smoothened pulseamplitudes S, it is possible to calculate a different correction degree,C', based on a ratio of the sum SD to a sum, SR, of the determined pulseamplitudes R. Otherwise, it is possible to calculate a differentcorrection degree by exchanging, in each of the two ratios, thenumerator and the denominator with each other. In the cases where theratios other than the ratio SD/SS are used, different criteria and/orreference values may be employed for judging whether the measurementcondition is proper.

While in the sixth embodiment the correction degree C is calculated fromthe determined and smoothened pulse amplitudes R, S which correspond toa prescribed range of cuff pressure values P_(c), it is possible toemploy a different cuff-pressure range, as needed. For example, all thefirst and second series of pulse amplitudes R, S that correspond to allthe cuff pressure values P_(c) may be used to determine the correctiondegree C. Otherwise, a first narrow cuff-pressure range whose centervalue corresponds to the systolic BP value of the subject and a secondnarrow cuff-pressure range whose center value corresponds to thediastolic BP value of the same may be employed for the same purpose. Inthese cases, too, different criteria and/or reference values may beemployed for judging whether the measurement condition is proper.

Although in the sixth embodiment the output device 738 provides therecording sheet 742 bearing one or both of the pulse-amplitudeindication 744 and the measurement-condition indication 746, it ispossible to modify the output device 738 such that the output device 738displays, on the image display panel thereof, one or both of the twoindications 744, 746.

It is to be understood that the present invention may be embodied withother changes, improvements, and modifications that may occur to thoseskilled in the art without departing from the scope and spirit of thepresent invention defined by the appended claims.

What is claimed is:
 1. An apparatus for measuring a blood pressure of aliving subject, comprising:a blood pressure measuring device whichmeasures a blood pressure value of the subject, said blood pressuremeasuring device comprising an inflatable cuff adapted to be woundaround a body portion of the subject; a first memory which stores aplurality of blood pressure values measured by said blood pressuremeasuring device, in an order of measurement of said blood pressurevalues; a pulse wave detecting device which detects a pulse waveproduced from an arterial vessel of the subject in synchronism withheartbeat of the subject while a pressure of said cuff of said bloodpressure measuring device is changed to measure each of said bloodpressure values; a second memory which stores a waveform of said pulsewave detected by said pulse wave detecting device, in said order, saidsecond memory storing the respective waveforms of the pulse waves eachof which is detected by said pulse wave detecting device while acorresponding one of said blood pressure values is measured by saidblood pressure measuring device; an output device which outputs saidblood pressure values stored in said first memory, in said order, and aplurality of curves respectively representing said waveforms stored insaid second memory, in said order, in a side-by-side relation with eachother; and an amplitude modifying means for modifying an amplitude ofeach of the waveforms detected by said pulse wave detecting device, sothat the waveforms output by said output device have a prescribedamplitude.
 2. An apparatus according to claim 1, wherein said pulse wavedetecting device comprises a sensor which detects, as said pulse wave, apressure oscillation produced in said cuff in synchronism with heartbeatof the subject.
 3. An apparatus according to claim 1, further comprisingwavelength modifying means for modifying a wavelength of each of thewaveforms detected by said pulse wave detecting device, so that thewaveforms output by said output device have a prescribed wavelength. 4.An apparatus according to claim 1, further comprising:evaluating meansfor evaluating a characteristic of each of the waveforms detected bysaid pulse wave detecting device, and providing an evaluated value ofsaid each waveform; and a third memory which stores said evaluated valueof said each waveform, in said order, wherein said output device outputsthe evaluated values stored in said third memory, in said order.
 5. Anapparatus according to claim 4, wherein said output device comprisesmeans for outputting a first graphical representation indicating saidblood pressure values stored in said first memory, and a secondgraphical representation indicating said evaluated values stored in saidthird memory, along a common axis indicative of time, and outputtingsaid curves representing said waveforms stored in said second memory,along said common axis.
 6. An apparatus for measuring a blood pressureof a living subject, comprising:a blood pressure measuring device whichmeasures a blood pressure value of the subject; a first memory whichstores a plurality of blood pressure values measured by said bloodpressure measuring device, in an order of measurement of said bloodpressure values; a pulse wave detecting device which detects a pulsewave produced from an arterial vessel of the subject in synchronism withheartbeat of the subject while each of said blood pressure values ismeasured by said blood pressure measuring device; a second memory whichstores a waveform of said pulse wave detected by said pulse wavedetecting device, in said order, said second memory storing therespective waveforms of the pulse waves each of which is detected bysaid pulse wave detecting device while a corresponding one of said bloodpressure values is measured by said blood pressure measuring device; anoutput device which outputs said blood pressure values stored in saidfirst memory, in said order, and a plurality of curves respectivelyrepresenting said waveforms stored in said second memory, in said order,in a side-by-side relation with each other; evaluating means forevaluating a characteristic of each of the waveforms detected by saidpulse wave detecting device, and providing an evaluated value of saideach waveform; and a third memory which stores said evaluated value ofsaid each waveform, in said order, wherein said output device outputsthe evaluated values stored in said third memory, in said order.
 7. Anapparatus according to claim 6, wherein said output device comprisesmeans for outputting a first graphical representation indicating saidblood pressure values stored in said first memory, and a secondgraphical representation indicating said evaluated values stored in saidthird memory, along a common axis indicative of time, and outputtingsaid curves representing said waveforms stored in said second memory,along said common axis.